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Li L, Ren DD, Zhang PY, Song YP, Li TX, Gao MH, Xu JN, Zhou L, Zeng ZC, Pu Q. Pushing the Limits of Capacitively Coupled Contactless Conductivity Detection for Capillary Electrophoresis. Anal Chem 2024. [PMID: 38863415 DOI: 10.1021/acs.analchem.4c01367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2024]
Abstract
Capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C4D) has proven to be an efficient technique for the separation and detection of charged inorganic, organic, and biochemical analytes. It offers several advantages, including cost-effectiveness, nanoliter injection volume, short analysis time, good separation efficiency, suitability for miniaturization, and portability. However, the routine determination of common inorganic cations (NH4+, K+, Na+, Ca2+, Mg2+, and Li+) and inorganic anions (F-, Cl-, Br-, NO2-, NO3-, PO43-, and SO42-) in water quality monitoring typically exhibits limits of detection of about 0.3-1 μM without preconcentration. This sensitivity often proves insufficient for the applications of CE-C4D in trace analysis situations. Here, we explore methods to push the detection limits of CE-C4D through a comprehensive consideration of signal and noise sources. In particular, we (i) studied the model of C4D and its guiding roles in C4D and CE-C4D, (ii) optimized the bandwidth and noise performance of the current-to-voltage (I-V) converter, and (iii) reduced the noise level due to the strong background signal of the background electrolyte by adaptive differential detection. We characterized the system with Li+; the 3-fold signal-to-noise (S/N) detection limit for Li+ was determined at 20 nM, with a linear range spanning from 60 nM to 1.6 mM. Moreover, the optimized CE-C4D method was applied to the analysis of common mixed inorganic cations (K+, Na+, Ca2+, Mg2+, and Li+), anions (F-, Cl-, Br-, NO2-, NO3-, PO43-, and SO42-), toxic halides (BrO3-) and heavy metal ions (Pb2+, Cd2+, Cr3+, Co2+, Ni2+, Zn2+, and Cu2+) at trace concentrations of 200 nM. All electropherograms showed good S/N ratios, thus proving its applicability and accuracy. Our results have shown that the developed CE-C4D method is feasible for trace ion analysis in water quality control.
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Affiliation(s)
- Lin Li
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
| | - Dou-Dou Ren
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
| | - Peng-Yu Zhang
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
| | - Yun-Peng Song
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
| | - Tang-Xiu Li
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
| | - Ming-Hui Gao
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
| | - Jia-Nan Xu
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
| | - Lei Zhou
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
| | - Zhi-Cong Zeng
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
| | - Qiaosheng Pu
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
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Li L, Song YP, Ren DD, Li TX, Gao MH, Zhou L, Zeng ZC, Pu QA. A compact and high-performance setup of capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C 4D). Analyst 2024; 149:3034-3040. [PMID: 38624147 DOI: 10.1039/d4an00354c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
Capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C4D) has the advantages of high throughput (simultaneous detection of multiple ions), high separation efficiency (higher than 105 theoretical plates) and rapid analysis capability (less than 5 min for common inorganic ions). A compact CE-C4D system is ideal for water quality control and on-site analysis. It is suitable not only for common cations (e.g. Na+, K+, Li+, NH4+, Ca2+, etc.) and anions (e.g. Cl-, SO42-, BrO3-, etc.) but also for some ions (e.g. lanthanide ions, Pb2+, Cd2+, etc.) that require complex derivatization procedures to be detected by ion chromatography (IC). However, an obvious limitation of the CE-C4D method is that its sensitivity (e.g. 0.3-1 μM for common inorganic ions) is often insufficient for trace analysis (e.g. 1 ppb or 20 nM level for common inorganic ions) without preconcentration. For this technology to become a powerful and routine analytical technique, the system should be made compact while maintaining trace analysis sensitivity. In this study, we developed an all-in-one version of the CE-C4D instrument with custom-made modular components to make it a convenient, compact and high-performance system. The system was designed using direct digital synthesis (DDS) technology to generate programmable sinusoidal waveforms with any frequency for excitation, a kilovolt high-voltage power supply for capillary electrophoresis separation, and an "effective" differential C4D cell with a low-noise circuitry for high-sensitivity detection. We characterized the system with different concentrations of Cs+, and even a low concentration of 20 nM was detectable without preconcentration. Moreover, the optimized CE-C4D setup was applied to analyse mixed ions at a trace concentration of 200 nM with excellent signal-to-noise ratios. In typical applications, the limits of detection based on the 3σ criterion (without baseline filtering) were 9, 10, 24, 5, and 12 nM for K+, Cs+, Li+, Ca2+, and Mg2+, respectively, and about 7, 6, 6 and 6 nM for Br-, ClO4-, BrO3- and SO42-, respectively. Finally, the setup was also applied for the analysis of all 14 lanthanide ions and rare-earth minerals, and it showed an improvement in sensitivity by more than 25 times.
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Affiliation(s)
- Lin Li
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, China.
| | - Yun-Peng Song
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, China.
| | - Dou-Dou Ren
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, China.
| | - Tang-Xiu Li
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, China.
| | - Ming-Hui Gao
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, China.
| | - Lei Zhou
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, China.
| | - Zhi-Cong Zeng
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, China.
| | - Qi-Aosheng Pu
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, China.
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Tůma P. Steady state microdialysis of microliter volumes of body fluids for monitoring of amino acids by capillary electrophoresis with contactless conductivity detection. Anal Chim Acta 2024; 1287:342113. [PMID: 38182349 DOI: 10.1016/j.aca.2023.342113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 12/03/2023] [Accepted: 12/04/2023] [Indexed: 01/07/2024]
Abstract
BACKGROUND The availability of dialysis membranes in the form of hollow fibres with diameters compatible with the fused silica capillaries used in capillary electrophoresis is very limited. However, haemodialysis bicarbonate cartridges commonly used in human medicine containing polysulfone hollow fibres are available on the market and are used for the fabrication of coaxial microdialysis probes. The miniature probe design ensures that steady-state conditions are achieved during microdialysis of minimal volumes of body fluids. RESULTS A coaxial microdialysis probe with a length of 5 cm and an inner diameter of 200 μm is used for microdialysis of 10 μL of body fluid collected into a sampling fused silica capillary with an inner diameter 430 μm. Microdialysis is performed into 0.01 M HCl as a perfusate at stopped flow and 2 μL of the resulting microdialysate are subjected to analysis by capillary electrophoresis with contactless conductivity detection. Microdialysis pre-treatment is verified by analysis of 11 common amino acids at a 100 μM concentration level, resulting in recoveries of 98.3-102.5%. The electrophoretic separation of amino acids is performed in 8.5 M acetic acid at pH 1.37 as a background electrolyte with analysis time up to 4.5 min and LOD in the range of 0.12-0.28 μM. The reproducibility of the developed technique determined for the peak area ranges from 1.2 to 4.5%. Applicability is tested in the quantification of valine and leucine in plasma during fasting and subsequent reconvalescence. SIGNIFICANCE The fabrication of a coaxial microdialysis probe for the laboratory preparation of microliter volumes of various types of clinical samples is described, which is coupled off-line with capillary electrophoretic monitoring of amino acids in 2 μL volumes of microdialysate. The developed methodology is suitable for quantification of 20 amino acids in whole human blood, plasma, tears and has potential for analysis of dry blood spots captured on hollow fibre.
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Affiliation(s)
- Petr Tůma
- Department of Hygiene, Third Faculty of Medicine, Charles University, Ruská 87, 100 00, Prague, 10, Czechia.
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Gojda J, Koudelková K, Ouřadová A, Lang A, Krbcová M, Gvozdeva A, Šebo V, Slagmolen L, Potočková J, Tůma P, Rossmeislová L, Anděl M, Karpe F, Schlesinger S. Severe COVID-19 associated hyperglycemia is caused by beta cell dysfunction: a prospective cohort study. Nutr Diabetes 2023; 13:11. [PMID: 37460458 DOI: 10.1038/s41387-023-00241-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 05/11/2023] [Accepted: 06/29/2023] [Indexed: 07/20/2023] Open
Abstract
BACKGROUND COVID-19, an infectious disease caused by SARS-CoV-2, was shown to be associated with an increased risk of new-onset diabetes. Mechanisms contributing to the development of hyperglycemia are still unclear. We aimed to study whether hyperglycemia is related to insulin resistance and/or beta cell dysfunction. MATERIALS AND METHODS Survivors of severe COVID-19 but without a known history of diabetes were examined at baseline (T0) and after 3 (T3) and 6 (T6) months: corticosteroids use, indirect calorimetry, and OGTT. Insulin response and sensitivity (IS) were expressed as insulinogenic (IGI), disposition (DI), and Matsuda insulin sensitivity index (ISI). Resting energy expenditure (REE) and respiratory quotient (RQ) was calculated from the gas exchange and nitrogen losses. RESULTS 26 patients (out of 37) with complete outcome data were included in the analysis (age ~59.0 years; BMI ~ 30.4, 35% women). Patients were hypermetabolic at T0 (30.3 ± 4.0 kcal/kg lean mass/day, ~120% predicted) but REE declined over 6 months (ΔT6-T0 mean dif. T6-T0 (95% CI): -5.4 (-6.8, -4.1) kcal/kg FFM/day, p < 0.0001). 17 patients at T0 and 13 patients at T6 had hyperglycemia. None of the patients had positive islet autoantibodies. Insulin sensitivity in T0 was similarly low in hyperglycemic (H) and normoglycemic patients (N) (T0 ISIH = 3.12 ± 1.23, ISIN = 3.47 ± 1.78, p = 0.44), whereas insulin response was lower in the H group (DIH = 3.05 ± 1.79 vs DIN = 8.40 ± 5.42, p = 0.003). Over 6 months ISI (ΔT6-T0 mean dif. T6-T0 for ISI (95% CI): 1.84 (0.45, 3.24), p = 0.01)) increased in the H group only. CONCLUSIONS Patients with severe COVID-19 had increased REE and insulin resistance during the acute phase due to the infection and corticosteroid use, but these effects do not persist during the follow-up period. Only patients with insufficient insulin response developed hyperglycemia, indicating that beta cell dysfunction, rather than insulin resistance, was responsible for its occurrence.
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Affiliation(s)
- Jan Gojda
- Department of Internal Medicine, Third Faculty of Medicine, Charles University, and Královské Vinohrady University Hospital, Prague, Czech Republic.
| | - Kateřina Koudelková
- Department of Internal Medicine, Third Faculty of Medicine, Charles University, and Královské Vinohrady University Hospital, Prague, Czech Republic
| | - Anna Ouřadová
- Department of Internal Medicine, Third Faculty of Medicine, Charles University, and Královské Vinohrady University Hospital, Prague, Czech Republic
| | - Alexander Lang
- Institute for Biometrics and Epidemiology, German Diabetes Center (Deutsches Diabetes-Zentrum/DDZ), Leibniz Center for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- German Center for Diabetes Research (DZD), Partner Düsseldorf, Düsseldorf, Germany
| | - Magdaléna Krbcová
- Department of Internal Medicine, Third Faculty of Medicine, Charles University, and Královské Vinohrady University Hospital, Prague, Czech Republic
| | - Alexandra Gvozdeva
- Department of Internal Medicine, Third Faculty of Medicine, Charles University, and Královské Vinohrady University Hospital, Prague, Czech Republic
| | - Viktor Šebo
- Department of Pathophysiology, Third Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Lotte Slagmolen
- Faculty of Movement and Rehabilitation Sciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Jana Potočková
- Department of Internal Medicine, Third Faculty of Medicine, Charles University, and Královské Vinohrady University Hospital, Prague, Czech Republic
| | - Petr Tůma
- Department of Hygiene, Third Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Lenka Rossmeislová
- Institute for Biometrics and Epidemiology, German Diabetes Center (Deutsches Diabetes-Zentrum/DDZ), Leibniz Center for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Michal Anděl
- Department of Internal Medicine, Third Faculty of Medicine, Charles University, and Královské Vinohrady University Hospital, Prague, Czech Republic
| | - Fredrik Karpe
- Oxford Center for Diabetes, Endocrinology, and Metabolism, University of Oxford, Oxford, UK
| | - Sabrina Schlesinger
- German Center for Diabetes Research (DZD), Partner Düsseldorf, Düsseldorf, Germany
- Department of Pathophysiology, Third Faculty of Medicine, Charles University, Prague, Czech Republic
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Tůma P, Sommerová B, Koval D, Šiklová M, Koc M. Plasma levels of creatine, 2-aminobutyric acid, acetyl-carnitine and amino acids during fasting measured by counter-current electrophoresis in PAMAPTAC capillary. Microchem J 2023. [DOI: 10.1016/j.microc.2023.108426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Tůma P. Monitoring of biologically active substances in clinical samples by capillary and microchip electrophoresis with contactless conductivity detection: A review. Anal Chim Acta 2022; 1225:340161. [DOI: 10.1016/j.aca.2022.340161] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 07/08/2022] [Accepted: 07/08/2022] [Indexed: 12/11/2022]
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Tůma P, Jaček M, Sommerová B, Dlouhý P, Jarošíková R, Husáková J, Wosková V, Fejfarová V. Monitoring of amoxicilline and ceftazidime in the microdialysate of diabetic foot and serum by capillary electrophoresis with contactless conductivity detection. Electrophoresis 2022; 43:1129-1139. [PMID: 35072285 DOI: 10.1002/elps.202100366] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 12/17/2021] [Accepted: 12/23/2021] [Indexed: 11/11/2022]
Abstract
Determination of the broad-spectrum antibiotics amoxicilline (AMX) and ceftazidime (CTZ) in blood serum and microdialysates of the subcutaneous tissue of the lower limbs is performed using CE with contactless conductivity detection (C4 D). Baseline separation of AMX is achieved in 0.5 M acetic acid as the background electrolyte and separation of CTZ in 3.2 M acetic acid with addition of 13% v/v methanol. The CE-C4 D determination is performed in a 25 µm capillary with suppression of the EOF using INST-coating on an effective length of 18 cm and the attained migration time is 4.2 min for AMX and 4.4 min for CTZ. The analysis was performed using 20 µl of serum and 15 µl of microdialysate, treated by the addition of acetonitrile in a ratio of 1/3 v/v and the sample is injected into the capillary using the large volume sample stacking technique. The LOQ attained in the microdialysate is 148 ng/ml for AMX and 339 ng/ml for CTZ, and in serum 143 ng/ml for AMX and 318 ng/ml for CTZ. The CE-C4 D method is employed for monitoring the passage of AMX and CTZ from the blood circulatory system into the subcutaneous tissue at the sites of diabetic ulceration in patients suffering from diabetic foot syndrome and also for measuring the pharmacokinetics following intravenous application of bolus antibiotic doses.
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Affiliation(s)
- Petr Tůma
- Department of Hygiene, Third Faculty of Medicine, Charles University, Prague 10, Czech Republic
| | - Martin Jaček
- Department of Hygiene, Third Faculty of Medicine, Charles University, Prague 10, Czech Republic
| | - Blanka Sommerová
- Department of Hygiene, Third Faculty of Medicine, Charles University, Prague 10, Czech Republic
| | - Pavel Dlouhý
- Department of Hygiene, Third Faculty of Medicine, Charles University, Prague 10, Czech Republic
| | - Radka Jarošíková
- Diabetes Centre, Institute for Clinical and Experimental Medicine, Prague 4, Czech Republic
| | - Jitka Husáková
- Diabetes Centre, Institute for Clinical and Experimental Medicine, Prague 4, Czech Republic
| | - Veronika Wosková
- Diabetes Centre, Institute for Clinical and Experimental Medicine, Prague 4, Czech Republic
| | - Vladimíra Fejfarová
- Diabetes Centre, Institute for Clinical and Experimental Medicine, Prague 4, Czech Republic
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Yang X, He L, Xu Z. Pressure-assisted electrokinetic injection for the stacking of biogenic amines gives enhancement factor up to 1000 in CE with UV detection. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2022; 14:1782-1787. [PMID: 35475508 DOI: 10.1039/d2ay00430e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Pressure-assisted electrokinetic injection (PAEKI) was applied for stacking of positively charged biogenic amines (BAs) to improve the sensitivity of capillary electrophoresis (CE). It is well known that the essential step for PAEKI is finding a stationary state of the running buffer such that the movement of the running buffer due to electroosmotic flow (EOF) is counterbalanced by external pressure in the opposite direction of the EOF under a given electric field. In order to find the balance point systematically and integrally, we studied the velocity of the whole BGE in the capillary by the impetus of opposite direction pressure (-0.1 to -0.6 psi), and the velocity of EOF with different voltages. According to the two sets of linear data, the EOF of CE coupled with PAEKI could be counterbalanced at the opposite direction pressure (-0.1 psi) and voltage (7.8 kV). In this study, the injection time was extended up to 0.35 min for all BAs and 0.70 min for the direct ultraviolet (UV) detection of BAs. Compared with hydrodynamic injection (HDI), the enrichment factors for sample injection times of 0.35 min and 0.70 min were 480-fold and 970-fold, respectively. The limits of detection (LODs) (S/N = 3) of indirect and direct UV detection were respectively 8.7-24.3 nmol L-1 and 0.4-4.5 nmol L-1, which reaches the sensitivity of high-performance liquid chromatography-mass spectrophotometry (HPLC-MS). With appropriate sample dilution, PAEKI can be used in the analysis of BAs in chicken.
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Affiliation(s)
- Xue Yang
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China.
| | - Lili He
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China.
| | - Zhongqi Xu
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China.
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He Y, Huang Q, He Y, Ji H, Zhang T, Wang B, Huang Z. A Low Excitation Working Frequency Capacitively Coupled Contactless Conductivity Detection (C 4D) Sensor for Microfluidic Devices. SENSORS 2021; 21:s21196381. [PMID: 34640701 PMCID: PMC8512373 DOI: 10.3390/s21196381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 09/14/2021] [Accepted: 09/20/2021] [Indexed: 11/16/2022]
Abstract
In this work, a new capacitively coupled contactless conductivity detection (C4D) sensor for microfluidic devices is developed. By introducing an LC circuit, the working frequency of the new C4D sensor can be lowered by the adjustments of the inductor and the capacitance of the LC circuit. The limits of detection (LODs) of the new C4D sensor for conductivity/ion concentration measurement can be improved. Conductivity measurement experiments with KCl solutions were carried out in microfluidic devices (500 µm × 50 µm). The experimental results indicate that the developed C4D sensor can realize the conductivity measurement with low working frequency (less than 50 kHz). The LOD of the C4D sensor for conductivity measurement is estimated to be 2.2 µS/cm. Furthermore, to show the effectiveness of the new C4D sensor for the concentration measurement of other ions (solutions), SO42− and Li+ ion concentration measurement experiments were also carried out at a working frequency of 29.70 kHz. The experimental results show that at low concentrations, the input-output characteristics of the C4D sensor for SO42− and Li+ ion concentration measurement show good linearity with the LODs estimated to be 8.2 µM and 19.0 µM, respectively.
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Affiliation(s)
| | | | | | - Haifeng Ji
- Correspondence: ; Tel.: +86-571-8795-2145
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Twenty years of amino acid determination using capillary electrophoresis: A review. Anal Chim Acta 2021; 1174:338233. [DOI: 10.1016/j.aca.2021.338233] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 01/14/2021] [Accepted: 01/16/2021] [Indexed: 12/28/2022]
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Piestansky J, Matuskova M, Cizmarova I, Olesova D, Mikus P. Determination of Branched-Chain Amino Acids in Food Supplements and Human Plasma by a CE-MS/MS Method with Enhanced Resolution. Int J Mol Sci 2021; 22:ijms22158261. [PMID: 34361026 PMCID: PMC8348851 DOI: 10.3390/ijms22158261] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 07/29/2021] [Accepted: 07/29/2021] [Indexed: 12/16/2022] Open
Abstract
In the presented study, a capillary electrophoresis-mass spectrometry method combining high separation efficiency and sensitive detection has been developed and validated, for the first time, to quantify branched chain amino acids (valine, isoleucine, leucine) in commercial food and sport supplement samples and human plasma samples. The separations were performed in a bare fused silica capillary. The background electrolyte was composed of 500 mM formic acid with pH 2.0. The plasma sample pretreatment was realized by simple protein precipitation with acetonitrile. Injection of a short zone of highly basic electrolyte before the sample injection and application of the negative pressure on the separation were accompanied by enhanced resolution of the isobaric amino acids—isoleucine and leucine. The developed method was characterized by favorable validation parameters, such as linearity (r2 > 0.99), accuracy and precision, the limit of detection, lower limit of quantification, or robustness. These parameters were more than sufficient for the quantification of branched chain amino acids in various samples. The determined concentrations of branched chain amino acids in food and sports supplements were in very good agreement with the content declared by the manufacturer. The investigated concentrations of branched chain amino acids were in the range 294.68–359.24 µM for valine, 91.76–95.67 µM for isoleucine, and 196.78–251.24 µM for leucine. These concentrations fall within the physiological limits. The developed CE-MS/MS method represents a suitable alternative to traditional approaches used in branched chain amino acid quality control and bioanalysis.
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Affiliation(s)
- Juraj Piestansky
- Department of Pharmaceutical Analysis and Nuclear Pharmacy, Faculty of Pharmacy, Comenius University, Odbojarov 10, SK-832 32 Bratislava, Slovakia; (M.M.); (I.C.)
- Toxicologic and Antidoping Center, Faculty of Pharmacy, Comenius University, Odbojarov 10, SK-832 32 Bratislava, Slovakia
- Correspondence: (J.P.); (P.M.); Tel.: +421-2-50-117-250 (J.P.); +421-2-50-117-243 (P.M.)
| | - Michaela Matuskova
- Department of Pharmaceutical Analysis and Nuclear Pharmacy, Faculty of Pharmacy, Comenius University, Odbojarov 10, SK-832 32 Bratislava, Slovakia; (M.M.); (I.C.)
| | - Ivana Cizmarova
- Department of Pharmaceutical Analysis and Nuclear Pharmacy, Faculty of Pharmacy, Comenius University, Odbojarov 10, SK-832 32 Bratislava, Slovakia; (M.M.); (I.C.)
| | - Dominika Olesova
- Institute of Neuroimmunology, Slovak Academy of Science, Dubravska cesta 9, SK-845 10 Bratislava, Slovakia;
| | - Peter Mikus
- Department of Pharmaceutical Analysis and Nuclear Pharmacy, Faculty of Pharmacy, Comenius University, Odbojarov 10, SK-832 32 Bratislava, Slovakia; (M.M.); (I.C.)
- Toxicologic and Antidoping Center, Faculty of Pharmacy, Comenius University, Odbojarov 10, SK-832 32 Bratislava, Slovakia
- Correspondence: (J.P.); (P.M.); Tel.: +421-2-50-117-250 (J.P.); +421-2-50-117-243 (P.M.)
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Tůma P, Hložek T, Kamišová J, Gojda J. Monitoring of circulating amino acids in patients with pancreatic cancer and cancer cachexia using capillary electrophoresis and contactless conductivity detection. Electrophoresis 2021; 42:1885-1891. [PMID: 34228371 DOI: 10.1002/elps.202100174] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 07/01/2021] [Accepted: 07/02/2021] [Indexed: 11/12/2022]
Abstract
Branched chain amino acids (BCAAs), alanine and glutamine are determined in human plasma by capillary electrophoresis with contactless conductivity detection (CE/C4 D). The baseline separation of five amino acids from other plasma components is achieved on the short capillary effective length of 18 cm in 3.2 mol/L acetic acid with addition of 13% v/v methanol as background electrolyte. Migration times range from 2.01 min for valine to 2.84 min for glutamine, and LODs for untreated plasma are in the interval 0.7-0.9 μmol/L. Sample treatment is based on the addition of acetonitrile to only 15 μL of plasma and supernatant is directly subjected to CE/C4 D. Circulating amino acids are measured in patients with pancreatic cancer and cancer cachexia during oral glucose tolerance test. It is shown that patients with pancreatic cancer and cancer cachexia syndrome exhibit low basal circulating BCAAs and glutamine levels and loss of their insulin-dependent suppression.
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Affiliation(s)
- Petr Tůma
- Third Faculty of Medicine, Department of Hygiene, Charles University, Prague, Czechia
| | - Tomáš Hložek
- Third Faculty of Medicine, Department of Hygiene, Charles University, Prague, Czechia
| | - Jana Kamišová
- Third Faculty of Medicine, Department of Internal Medicine, Charles University and Královské Vinohrady University Hospital, Prague, Czechia.,Centre for the Research on Diabetes, Metabolism and Nutrition, Third Faculty of Medicine, Prague, Czechia
| | - Jan Gojda
- Third Faculty of Medicine, Department of Internal Medicine, Charles University and Královské Vinohrady University Hospital, Prague, Czechia.,Centre for the Research on Diabetes, Metabolism and Nutrition, Third Faculty of Medicine, Prague, Czechia
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De Silva M, Opallage PM, Dunn RC. Direct detection of inorganic ions and underivatized amino acids in seconds using high-speed capillary electrophoresis coupled with back-scatter interferometry. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2021; 13:1340-1348. [PMID: 33491683 DOI: 10.1039/d0ay02218g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
High speed capillary electrophoresis (HSCE) combined with refractive index (RI) detection is developed for the rapid separation and detection of inorganic ions and amino acids. A mixture of three inorganic ions (K+, Na+, Li+) and eight amino acids (Lys, Arg, Ala, Gly, Val, Thr, Trp, Asp) are detected using back scatter interferometry (BSI), without the need for chemical modifications or contrast. A thin-walled separation capillary (50 μm i.d. by 80 μm o.d.) helps mitigate Joule heating at the high field strengths required for rapid separations. This, combined with a short 8 cm length-to-detector (10 cm total length), enables separations on the seconds time scale. Using a background electrolyte (BGE) of 4 M acetic acid (pH 1.6) and a field strength of 900 V cm-1, all 11 analytes are separated in less than 40 s. Moreover, peaks in the BSI signal arising from the sample injection and EOF, enable electrophoretic mobilities to readily be obtained from apparent mobilities. This leads to excellent repeatability, with analyte electrophoretic mobilities varying from 0.39 to 1.56 % RSD over eight consecutive separations. The universal detection of inorganic ions and amino acids without prior chemical modification or additives in the BGE is an advantage of refractive index detection. A disadvantage arises from modest detection limits. Here, however, we show that submicromolar detection is possible with careful thermostatting of the thin separation capillary. A series of electropherograms are used to quantify arginine concentrations from 700 nM to 500 μM, using 50 μM Li+ as an internal standard. The resulting calibration curve leads to a calculated LOD of 376 nM and a LOQ of 1.76 μM. Diagnostically relevant amino acid panels are also separated, illustrating the potential for future applications in neurodegenerative and metabolic disease diagnostics. HSCE combined with BSI detection, therefore, is shown to be a rapid, sensitive, and universal approach for analyzing sample mixtures.
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Affiliation(s)
- Miyuru De Silva
- Ralph N. Adams Institute for Bioanalytical Chemistry, University of Kansas, 2030 Becker Drive, Lawrence, KS 66047, USA.
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Tůma P. Determination of amino acids by capillary and microchip electrophoresis with contactless conductivity detection - Theory, instrumentation and applications. Talanta 2020; 224:121922. [PMID: 33379123 DOI: 10.1016/j.talanta.2020.121922] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 11/22/2020] [Accepted: 11/23/2020] [Indexed: 01/15/2023]
Abstract
This review article summarises aspects of the determination of amino acids using capillary and chip electrophoresis in combination with contactless conductivity detection from their historical beginnings to the present time. Discussion is included of the theory of conductivity detection in electromigration techniques, the design of contactless conductivity cells for detection in capillaries and on microchips, including the use of computer programs for simulation of the conductivity response and the process of the electrophoretic separation of amino acids. Emphasis is placed on optimisation of the background electrolyte composition, chiral separation, multidimensional separation, stacking techniques and the use of multidetection systems. There is also a description of clinical applications, the determination of amino acids in foodstuffs, waters, soils and composts with emphasis on modern techniques of sample treatment, such as microdialysis, liquid membrane extraction and many other techniques.
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Affiliation(s)
- Petr Tůma
- Department of Hygiene, Third Faculty of Medicine, Charles University, Ruská 87, 100 00, Prague 10, Czech Republic.
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15
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Pont L, Barbosa J, Benavente F. A rapid and simple method for the determination of organic acids in proteolytic enzymes by capillary electrophoresis with indirect ultraviolet detection. Microchem J 2020. [DOI: 10.1016/j.microc.2020.105204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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16
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Celá A, Glatz Z. Homocyclic
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‐dicarboxaldehydes: Derivatization reagents for sensitive analysis of amino acids and related compounds by capillary and microchip electrophoresis. Electrophoresis 2020; 41:1851-1869. [DOI: 10.1002/elps.202000041] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 05/27/2020] [Accepted: 06/07/2020] [Indexed: 01/01/2023]
Affiliation(s)
- Andrea Celá
- Department of Biochemistry, Faculty of Science Masaryk University Brno Czech Republic
| | - Zdeněk Glatz
- Department of Biochemistry, Faculty of Science Masaryk University Brno Czech Republic
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Measuring venous-arterial differences of valine, isoleucine, leucine, alanine and glutamine in skeletal muscles using counter-current electrophoresis with contactless conductivity detection. J Electroanal Chem (Lausanne) 2020. [DOI: 10.1016/j.jelechem.2019.113772] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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18
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Šimčíková D, Tůma P, Jegorov A, Šimek P, Heneberg P. Rapid methods for the separation of natural mixtures of beauverolides, cholesterol acyltransferase inhibitors, isolated from the fungus
Isaria fumosorosea. J Sep Sci 2020; 43:962-969. [DOI: 10.1002/jssc.201901084] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 12/03/2019] [Accepted: 12/09/2019] [Indexed: 12/22/2022]
Affiliation(s)
| | - Petr Tůma
- Charles UniversityThird Faculty of Medicine Prague Czech Republic
| | - Alexandr Jegorov
- Charles UniversityThird Faculty of Medicine Prague Czech Republic
- Biology CentreCzech Academy of Sciences České Budějovice Czech Republic
| | - Petr Šimek
- Biology CentreCzech Academy of Sciences České Budějovice Czech Republic
| | - Petr Heneberg
- Charles UniversityThird Faculty of Medicine Prague Czech Republic
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Liu Z, Tu MJ, Zhang C, Jilek JL, Zhang QY, Yu AM. A reliable LC-MS/MS method for the quantification of natural amino acids in mouse plasma: Method validation and application to a study on amino acid dynamics during hepatocellular carcinoma progression. J Chromatogr B Analyt Technol Biomed Life Sci 2019; 1124:72-81. [PMID: 31177050 DOI: 10.1016/j.jchromb.2019.05.039] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 05/17/2019] [Accepted: 05/31/2019] [Indexed: 01/15/2023]
Abstract
A simple and fast LC-MS/MS method was developed and validated for simultaneous quantification of 20 proteinogenic l-amino acids (AAs) in a small volume (5 μL) of mouse plasma. Chromatographic separation was achieved on an Intrada Amino Acid column within 13 min via gradient elution with an aqueous solution containing 100 mM ammonium formate and an organic mobile phase containing acetonitrile, water and formic acid (v:v:v = 95:5:0.3), at the flow rate of 0.6 mL/min. Individual AAs and corresponding stable-isotope-labeled AAs internal standards were analyzed by multiple reaction monitoring (MRM) in positive ion mode under optimized conditions. Method validation consisted of linearity, sensitivity, accuracy and precision, recovery, matrix effect, and stability, and the results demonstrated this LC-MS/MS method as a specific, accurate, and reliable assay. This LC-MS/MS method was thus utilized to compare the dynamics of individual plasma AAs between healthy and orthotopic hepatocellular carcinoma (HCC) xenograft mice housed under identical conditions. Our results revealed that, 5 weeks after HCC tumor progression, plasma l-arginine concentrations were significantly decreased in HCC mice while l-alanine and l-threonine levels were sharply increased. These findings support the utilities of this LC-MS/MS method and the promise of specific AAs as possible biomarkers for HCC.
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Affiliation(s)
- Zhenzhen Liu
- Department of Medical Function, Health Science Center, Yangtze University, Jingzhou, Hubei 434000, China; Department of Biochemistry & Molecular Medicine, School of Medicine, UC Davis, Sacramento, CA 95817, USA
| | - Mei-Juan Tu
- Department of Biochemistry & Molecular Medicine, School of Medicine, UC Davis, Sacramento, CA 95817, USA
| | - Chao Zhang
- Department of Biochemistry & Molecular Medicine, School of Medicine, UC Davis, Sacramento, CA 95817, USA
| | - Joseph L Jilek
- Department of Biochemistry & Molecular Medicine, School of Medicine, UC Davis, Sacramento, CA 95817, USA
| | - Qian-Yu Zhang
- Department of Biochemistry & Molecular Medicine, School of Medicine, UC Davis, Sacramento, CA 95817, USA
| | - Ai-Ming Yu
- Department of Biochemistry & Molecular Medicine, School of Medicine, UC Davis, Sacramento, CA 95817, USA.
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Pangavhane S, Makrlík E, Ruzza P, Kašička V. Affinity capillary electrophoresis employed for determination of stability constants of antamanide complexes with univalent and divalent cations in methanol. Electrophoresis 2019; 40:2321-2328. [DOI: 10.1002/elps.201900043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 04/18/2019] [Accepted: 04/29/2019] [Indexed: 12/31/2022]
Affiliation(s)
- Sachin Pangavhane
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences Prague Czechia
- University of Chemistry and Technology Prague Czechia
| | - Emanuel Makrlík
- Faculty of Environmental SciencesCzech University of Life Sciences Prague Czechia
| | - Paolo Ruzza
- Institute of Biomolecular Chemistry of CNR, Padua Unit Padua Italy
| | - Václav Kašička
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences Prague Czechia
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Tůma P, Sommerová B, Vaculín Š. Rapid electrophoretic monitoring of the anaesthetic ketamine and its metabolite norketamine in rat blood using a contactless conductivity detector to study the pharmacokinetics. J Sep Sci 2019; 42:2062-2068. [PMID: 30938060 DOI: 10.1002/jssc.201900116] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 03/28/2019] [Accepted: 03/28/2019] [Indexed: 01/23/2023]
Abstract
A method of capillary electrophoresis with contactless conductivity detection has been developed for non-enantioselective monitoring the anaesthetic ketamine and its main metabolite norketamine. The separation is performed in a 15 μm capillary with an overall length of 31.5 cm and length to detector of 18 cm; inner surface of the capillary is covered with a commercial coating solution to reduce the electroosmotic flow. In an optimised background electrolyte with composition 2 M acetic acid + 1% v/v coating solution under application of a high voltage of 30 kV, the migration time is 97.1 s for ketamine and 95.8 s for norketamine, with an electrophoretic resolution of 1.2. The attained detection limit was 83 ng/mL (0.3 μmol/L) for ketamine and 75 ng/mL (0.3 μmol/L) for norketamine; the number of theoretic plates for separation of an equimolar model mixture with a concentration of 2 μg/mL was 683 500 plates/m for ketamine and 695 400 plates/m for norketamine. Laboratory preparation of rat blood plasma is based on mixing 10 μL of plasma with 30 μL of acidified acetonitrile, followed by centrifugation. A pharmacokinetic study demonstrated an exponential decrease in the plasma concentration of ketamine after intravenous application and much slower kinetics for intraperitoneal application.
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Affiliation(s)
- Petr Tůma
- Department of Hygiene, Third Faculty of Medicine, Charles University, Prague, Czechia
| | - Blanka Sommerová
- Department of Hygiene, Third Faculty of Medicine, Charles University, Prague, Czechia
| | - Šimon Vaculín
- Department of Physiology, Third Faculty of Medicine, Charles University, Prague, Czechia
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Tůma P. The Control of Glucose and Lactate Levels in Nutrient Medium After Cell Incubation and in Microdialysates of Human Adipose Tissue by Capillary Electrophoresis with Contactless Conductivity Detection. Methods Mol Biol 2019; 1972:95-108. [PMID: 30847786 DOI: 10.1007/978-1-4939-9213-3_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Two methods of capillary electrophoresis with contactless conductivity detection have been developed for monitoring the levels of glucose and lactate in clinical samples. The separations are performed in uncoated fused silica capillaries with inner diameter 10 or 20 μm, total length 31.5 cm, length to detector 18 cm, using an Agilent electrophoretic instrument with an integrated contactless conductivity detector. Glucose is determined in optimized background electrolyte, 50 mM NaOH with pH 12.6 and 2-deoxyglucose is used as an internal standard; the determination of lactate is performed in 40 mM CHES/NaOH with pH 9.4 and lithium cations as an internal standard. Both substances are determined in minimal volumes of (1) nutrient media after cell incubation, and (2) microdialysates of human adipose tissue; after dilution and filtration as the only treatment of the sample. The migration time of glucose is 2.5 min and that of lactate is 1.5 min with detection limits at the micromolar concentration level. The developed techniques are suitable for sequential monitoring of glucose and lactate over time during metabolic experiments.
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Affiliation(s)
- Petr Tůma
- Department of Hygiene, Third Faculty of Medicine, Charles University, Prague, Czech Republic.
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23
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Tůma P, Sommerová B, Šiklová M. Monitoring of adipose tissue metabolism using microdialysis and capillary electrophoresis with contactless conductivity detection. Talanta 2019; 192:380-386. [DOI: 10.1016/j.talanta.2018.09.076] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 09/19/2018] [Accepted: 09/20/2018] [Indexed: 02/02/2023]
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24
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Rapid and Sensitive Determination of Branched-Chain Amino Acids in Human Plasma by Capillary Electrophoresis with Contactless Conductivity Detection for Physiological Studies. Methods Mol Biol 2019; 1972:15-24. [PMID: 30847781 DOI: 10.1007/978-1-4939-9213-3_2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Capillary electrophoresis (CE) with contactless conductivity detection (C4D) represents a strong tool for determining amino acids in clinical samples. This chapter provides detailed instructions for CE/C4D determination of the branched-chain amino acids (BCAAs) valine, isoleucine, and leucine in human plasma, which can be readily employed in physiological studies. Baseline separation of all the BCAAs is achieved on a short separation length equal to 18 cm in optimized background electrolyte consisting of 3.2 M acetic acid dissolved in 20% v/v methanol with addition of 1.0% v/v INST-coating solution. The analysis time does not exceed 3 min and the limit of detection is 0.4 μM for all BCAAs. The pretreatment of human plasma is very simple and is based on fourfold plasma dilution by acetonitrile and subsequent filtration. Only 50 μL of plasma is used for the analysis. The high sensitivity of the CE/C4D method is achieved by injecting a large volume of sample, combined with application of negative pressure to flush the acetonitrile zone out of the capillary.
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25
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Tůma P, Bursová M, Sommerová B, Horsley R, Čabala R, Hložek T. Novel electrophoretic acetonitrile-based stacking for sensitive monitoring of the antiepileptic drug perampanel in human serum. J Pharm Biomed Anal 2018; 160:368-373. [DOI: 10.1016/j.jpba.2018.08.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 08/01/2018] [Accepted: 08/03/2018] [Indexed: 12/28/2022]
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26
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20th anniversary of axial capacitively coupled contactless conductivity detection in capillary electrophoresis. Trends Analyt Chem 2018. [DOI: 10.1016/j.trac.2018.03.007] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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27
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Tůma P, Heneberg P, Vaculín Š, Koval D. Electrophoretic large volume sample stacking for sensitive determination of the anti-microbial agent pentamidine in rat plasma for pharmacological studies. Electrophoresis 2018; 39:2605-2611. [DOI: 10.1002/elps.201700440] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Revised: 12/18/2017] [Accepted: 12/19/2017] [Indexed: 01/27/2023]
Affiliation(s)
- Petr Tůma
- Department of Hygiene; Third Faculty of Medicine; Charles University; Prague Czechia
| | - Petr Heneberg
- Third Faculty of Medicine; Charles University; Prague Czechia
| | - Šimon Vaculín
- Department of Normal; Pathological and Clinical Physiology; Third Faculty of Medicine; Charles University; Prague Czechia
| | - Dušan Koval
- Institute of Organic Chemistry and Biochemistry; The Czech Academy of Sciences; Prague Czechia
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28
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Phillips TM. Recent advances in CE and microchip-CE in clinical applications: 2014 to mid-2017. Electrophoresis 2017; 39:126-135. [PMID: 28853177 DOI: 10.1002/elps.201700283] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Revised: 08/09/2017] [Accepted: 08/10/2017] [Indexed: 11/11/2022]
Abstract
CE and microchip CE (ME) are powerful tools for the analysis of a number of different analytes and have been applied to a variety of clinical fields and human samples. This review will present an overview of the most recent applications of these techniques to different areas of clinical medicine during the period of 2014 to mid-2017. CE and ME have been applied to clinical chemistry, drug detection and monitoring, hematology, infectious diseases, oncology, endocrinology, neonatology, nephrology, and genetic screening. Samples examined range from serum, plasma, and urine to lest utilized materials such as tears, cerebral spinal fluid, sweat, saliva, condensed breath, single cells, and biopsy tissue. Examples of clinical applications will be given along with the various detection systems employed.
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Affiliation(s)
- Terry M Phillips
- Department of Pharmaceutics, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, USA
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Poinsot V, Ong-Meang V, Ric A, Gavard P, Perquis L, Couderc F. Recent advances in amino acid analysis by capillary electromigration methods: June 2015-May 2017. Electrophoresis 2017; 39:190-208. [PMID: 28805963 DOI: 10.1002/elps.201700270] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 07/28/2017] [Accepted: 07/31/2017] [Indexed: 12/13/2022]
Abstract
In the tenth edition of this article focused on recent advances in amino acid analysis using capillary electrophoresis, we describe the most important research articles published on this topic during the period from June 2015 to May 2017. This article follows the format of the previous articles published in Electrophoresis. The new developments in amino acid analysis with CE mainly describe improvements in CE associated with mass spectrometry. Focusing on applications, we mostly describe clinical works, although metabolomics studies are also very important. Finally, works focusing on amino acids in food and agricultural applications are also described.
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Affiliation(s)
- Véréna Poinsot
- Laboratoire des IMRCP, Université Paul Sabatier, Université de Toulouse, France
| | | | - Audrey Ric
- Laboratoire des IMRCP, Université Paul Sabatier, Université de Toulouse, France
| | - Pierre Gavard
- Laboratoire des IMRCP, Université Paul Sabatier, Université de Toulouse, France
| | - Lucie Perquis
- Laboratoire des IMRCP, Université Paul Sabatier, Université de Toulouse, France
| | - François Couderc
- Laboratoire des IMRCP, Université Paul Sabatier, Université de Toulouse, France
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Song Y, Xu C, Kuroki H, Liao Y, Tsunoda M. Recent trends in analytical methods for the determination of amino acids in biological samples. J Pharm Biomed Anal 2017; 147:35-49. [PMID: 28927726 DOI: 10.1016/j.jpba.2017.08.050] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 08/25/2017] [Accepted: 08/26/2017] [Indexed: 12/13/2022]
Abstract
Amino acids are widely distributed in biological fluids and involved in many biological processes, such as the synthesis of proteins, fatty acids, and ketone bodies. The altered levels of amino acids in biological fluids have been found to be closely related to several diseases, such as type 2 diabetes, kidney disease, liver disease, and cancer. Therefore, the development of analytical methods to measure amino acid concentrations in biological samples can contribute to research on the physiological actions of amino acids and the prediction, diagnosis and understanding of diseases. This review describes the analytical methods reported in 2012-2016 that utilized liquid chromatography and capillary electrophoresis coupled with ultraviolet, fluorescence, mass spectrometry, and electrochemical detection. Additionally, the relationship between amino acid concentrations and several diseases is also summarized.
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Affiliation(s)
- Yanting Song
- Key Laboratory of Tropic Biological Resources, Minister of Education, Department of Pharmaceutical Sciences, College of Marine Science, Hainan University, Haikou 570228, China
| | - Chang Xu
- Key Laboratory of Tropic Biological Resources, Minister of Education, Department of Pharmaceutical Sciences, College of Marine Science, Hainan University, Haikou 570228, China
| | - Hiroshi Kuroki
- Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 1130033, Japan
| | - Yiyi Liao
- Key Laboratory of Tropic Biological Resources, Minister of Education, Department of Pharmaceutical Sciences, College of Marine Science, Hainan University, Haikou 570228, China
| | - Makoto Tsunoda
- Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 1130033, Japan.
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Qiu J, Wang J, Xu Z, Liu H, Ren J. Quantitation of underivatized branched-chain amino acids in sport nutritional supplements by capillary electrophoresis with direct or indirect UV absorbance detection. PLoS One 2017. [PMID: 28640882 PMCID: PMC5481027 DOI: 10.1371/journal.pone.0179892] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The branched-chain amino acids (BCAAs) including leucine (Leu), isoleucine (Ile) and valine (Val) play a pivotal role in the human body. Herein, we developed capillary electrophoresis (CE) coupled with conventional UV detector to quantify underivatized BCAAs in two kinds of sport nutritional supplements. For direct UV detection at 195 nm, the BCAAs (Leu, two enantiomers of Ile and Val) were separated in a background electrolyte (BGE) consisting of 40.0 mmol/L sodium tetraborate, and 40.0 mmol/L β-cyclodextrin (β-CD) at pH 10.2. In addition, the indirect UV detection at 264 nm was achieved in a BGE of 2.0 mmol/L Na2HPO4, 10.0 mmol/L p-aminosalicylic acid (PAS) as UV absorbing probe, and 40.0 mmol/L β-CD at pH 12.2. The β-CD significantly benefited the isomeric separation of Leu, L- and D-Ile. The optimal conditions allowed the LODs (limit of detections) of direct and indirect UV absorption detection to be tens μmol/L level, which was comparable to the reported CE inline derivatization method. The RSDs (relative standard deviations) of migration time and peak area were less than 0.91% and 3.66% (n = 6). Finally, CE with indirect UV detection method was applied for the quantitation of BCAAs in two commercial sport nutritional supplements, and good recovery and precision were obtained. Such simple CE method without tedious derivatization process is feasible of quality control and efficacy evaluation of the supplemental proteins.
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Affiliation(s)
- Jun Qiu
- Shanghai Research Institute of Sports Science, Shanghai, China
| | - Jinhao Wang
- Shanghai Research Institute of Sports Science, Shanghai, China
| | - Zhongqi Xu
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai, China
- * E-mail: (ZQX); (JR)
| | - Huiqing Liu
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai, China
| | - Jie Ren
- China Table Tennis College, Shanghai University of Sport, Shanghai, China
- * E-mail: (ZQX); (JR)
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Gojda J, Straková R, Plíhalová A, Tůma P, Potočková J, Polák J, Anděl M. Increased Incretin But Not Insulin Response after Oral versus Intravenous Branched Chain Amino Acids. ANNALS OF NUTRITION AND METABOLISM 2017; 70:293-302. [PMID: 28595189 DOI: 10.1159/000475604] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2016] [Accepted: 04/07/2017] [Indexed: 12/18/2022]
Abstract
BACKGROUND/AIMS Branched chain amino acids (BCAAs) are known to exert an insulinotropic effect. Whether this effect is mediated by incretins (glucagon like peptide 1 [GLP-1] or glucose-dependent insulinotropic peptide [GIP]) is not known. The aim of this study was to show whether an equivalent dose of BCAA elicits a greater insulin and incretin response when administered orally than intravenously (IV). METHODS Eighteen healthy, male subjects participated in 3 tests: IV application of BCAA solution, oral ingestion of BCAA and placebo in an equivalent dose (30.7 ± 1.1 g). Glucose, insulin, C-peptide, glucagon, GLP-1, GIP, valine, leucine and isoleucine concentrations were measured. RESULTS Rise in serum BCAA was achieved in both BCAA tests, with incremental areas under the curve (iAUC) being 2.1 times greater for IV BCAA compared with those of the oral BCAA test (p < 0.0001). Oral and IV BCAA induced comparable insulin response greater than placebo (240 min insulin iAUC: oral 3,411 ± 577 vs. IV 2,361 ± 384 vs. placebo 961.2 ± 175 pmol/L, p = 0.0006). Oral BCAA induced higher GLP-1 (p < 0.0001) and GIP response (p < 0.0001) compared with the IV or placebo. Glucose levels declined significantly (p < 0.001) in the same pattern during both BCAA tests with no change in the placebo group. CONCLUSIONS An equivalent dose of BCAA elicited a comparable insulin and greater incretin response when administered orally and not when administered through IV. We conclude that insulinotropic effects of BCAA are partially incretin dependent.
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Affiliation(s)
- Jan Gojda
- Centre for Research on Diabetes, Metabolism and Nutrition of Third Faculty of Medicine, Charles University in Prague, Prague, Czech Republic
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Chronic dietary exposure to branched chain amino acids impairs glucose disposal in vegans but not in omnivores. Eur J Clin Nutr 2017; 71:594-601. [DOI: 10.1038/ejcn.2016.274] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Revised: 12/02/2016] [Accepted: 12/16/2016] [Indexed: 12/18/2022]
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Tůma P. Frequency-tuned contactless conductivity detector for the electrophoretic separation of clinical samples in capillaries with very small internal dimensions. J Sep Sci 2017; 40:940-947. [PMID: 27995764 DOI: 10.1002/jssc.201601213] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 11/19/2016] [Accepted: 11/28/2016] [Indexed: 12/27/2022]
Abstract
An axial design of a capacitively coupled contactless conductivity detector was tested in combination with fused-silica capillaries with internal diameters of 10, 15, and 25 μm, which are used for high-efficiency electrophoretic separation. The transmission of the signal in the detection probe dependent on the specific conductivity of the solution in the capillary in the range 0-278 mS.m-1 has a complex character and a minimum appears on the curve at very low conductivities. The position of the minimum of the calibration dependence gradually shifts with decreasing frequency of the exciting signal from 1.0 to 0.25 MHz toward lower specific conductivity values. The presence of a minimum on the calibration curves is a natural property of the axial design of contactless conductivity detector, demonstrated by solution of the equivalent electrical circuit of the detection probe, and is specifically caused by the use of shielding foil. The behavior of contactless conductivity detector in the vicinity of the minimum was documented for practical separations of amino acids in solutions of 3.2 M acetic acid with addition of 0-50% v/v methanol.
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Affiliation(s)
- Petr Tůma
- Department of Biochemistry, Cell and Molecular Biology, Third Faculty of Medicine, Charles University, Prague, Czech Republic
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Grochocki W, Markuszewski MJ, Quirino JP. Simultaneous determination of creatinine and acetate by capillary electrophoresis with contactless conductivity detector as a feasible approach for urinary tract infection diagnosis. J Pharm Biomed Anal 2017; 137:178-181. [PMID: 28131056 DOI: 10.1016/j.jpba.2017.01.032] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 12/28/2016] [Accepted: 01/16/2017] [Indexed: 12/19/2022]
Abstract
Urinary tract infection (UTI) is one of the most common bacterial infection in human but its diagnosis is difficult. Metabolomic studies with nuclear magnetic resonance of urine have shown that acetic acid/creatinine ratio may be used for early UTI diagnosis. Here, a method for simultaneous determination of acetate and creatinine by capillary zone electrophoresis with contactless conductivity detector was developed for the first time. The separation was with 40mM MES and 20mM l-histidine as a background solution. The total time of a single run, including capillary conditioning, was less than 12min. The method was successfully demonstrated for analysis of actual and fortified human urine samples after methanol dilution. Analytical figures of merit such as linearity, LOQ, and repeatability (intraday and interday) were studied.
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Affiliation(s)
- Wojciech Grochocki
- Department of Biopharmaceutics and Pharmacodynamics, Medical University of Gdansk, Gdansk, Poland; Australian Centre for Research on Separation Science (ACROSS), School of Physical Sciences-Chemistry, University of Tasmania, Hobart, 7001, Australia
| | - Michał J Markuszewski
- Department of Biopharmaceutics and Pharmacodynamics, Medical University of Gdansk, Gdansk, Poland.
| | - Joselito P Quirino
- Australian Centre for Research on Separation Science (ACROSS), School of Physical Sciences-Chemistry, University of Tasmania, Hobart, 7001, Australia.
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Tůma P, Jaček M, Fejfarová V, Polák J. Electrophoretic stacking for sensitive determination of antibiotic ceftazidime in human blood and microdialysates from diabetic foot. Anal Chim Acta 2016; 942:139-145. [PMID: 27720117 DOI: 10.1016/j.aca.2016.09.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 08/29/2016] [Accepted: 09/10/2016] [Indexed: 12/30/2022]
Abstract
An electrophoretic stacking method has been developed for monitoring the therapeutic level of the antibiotic ceftazidime in blood plasma and microdialysates taken from peripheral soft tissues of the lower limbs of patients with diabetic foot syndrome. The biological samples are treated by addition of acetonitrile in an amount of 75% v/v and injected into a capillary in a large volume; after turning on the separation voltage, the residual acetonitrile is forced out of the capillary by the application of hydrodynamic pressure. The clinical samples were separated in an optimised background electrolyte composed of 50 mM chloroacetic acid +20% v/v methanol +0.5% v/v INST coating solution. The attained LOD for ceftazidime equalled 0.42 μg mL-1 (0.8 μM) and the migration time equalled 3.75 min when using a 25 μm capillary with minimum length of 31.5 cm. The separation was controlled by a maximum voltage of +30 kV and the movement of the analyte was accelerated by a pressure of 50 mbar. The RSD values for intra-day repeatability of the migration time and peak area are 0.14% and 3.8%, respectively; the inter-day values equalled 0.25% for the migration time and 7.3% for peak area, respectively. Pharmacological studies revealed that ceftazidime passes from the blood circulation to the peripheral tissues of the lower limbs with an efficiency of 20%. The introduction of CE control of ceftazidime level in diabetic foot represents a very important improvement in achieving the targeted therapeutic effect.
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Affiliation(s)
- Petr Tůma
- Charles University in Prague, Third Faculty of Medicine, Department of Biochemistry, Cell and Molecular Biology, Ruská 87, 100 00 Prague 10, Czech Republic.
| | - Martin Jaček
- Charles University in Prague, Third Faculty of Medicine, Department of Biochemistry, Cell and Molecular Biology, Ruská 87, 100 00 Prague 10, Czech Republic
| | - Vladimíra Fejfarová
- Institute for Clinical and Experimental Medicine, Diabetes Center, Vídeňská 1958, 140 21 Prague 4, Czech Republic
| | - Jan Polák
- Charles University in Prague, Third Faculty of Medicine, Center for Research on Diabetes, Metabolism and Nutrition, Ruská 87, Prague 10000, Czech Republic; 2nd Internal Medicine Department, Vinohrady Teaching Hospital, Šrobárova 50, Prague 10034, Czech Republic
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Kubáň P, Hauser PC. Contactless conductivity detection for analytical techniques- Developments from 2014 to 2016. Electrophoresis 2016; 38:95-114. [DOI: 10.1002/elps.201600280] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 08/05/2016] [Accepted: 08/06/2016] [Indexed: 11/09/2022]
Affiliation(s)
- Pavel Kubáň
- Institute of Analytical Chemistry of the Czech Academy of Sciences; Brno Czech Republic
| | - Peter C. Hauser
- Department of Chemistry; University of Basel; Basel Switzerland
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Abstract
PURPOSE OF REVIEW The concentrations of plasma-free amino acids, such as branched-chain amino acids and aromatic amino acids, are associated with visceral obesity, insulin resistance, and the future development of diabetes and cardiovascular diseases. This review discusses recent progress in the early assessment of the risk of developing diabetes and the reversal of altered plasma-free amino acids through interventions. Additionally, recent developments that have increased the utility of amino acid profiling technology are also described. RECENT FINDINGS Plasma-free amino acid alterations in the early stage of lifestyle-related diseases are because of obesity and insulin resistance-related inflammation, and these alterations are reversed by appropriate (nutritional, drug, or surgical) interventions that improve insulin sensitivity. For clinical applications, procedures for measuring amino acids are being standardized and automated. SUMMARY Plasma-free amino acid profiles have potential as biomarkers for both assessing diabetes risk and monitoring the effects of strategies designed to lower that risk. In addition, the methodology for measuring amino acids has been refined, with the goal of routine clinical application.
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Affiliation(s)
- Kenji Nagao
- aInstitute for Innovation, Ajinomoto Co., Inc., Kawasaki-ku, Kawasaki, Japan bStanford Prevention Research Center, Stanford University School of Medicine, Stanford, California, USA cCenter for Multiphasic Health Testing and Services, Mitsui Memorial Hospital, Izumicho, Chiyoda-ku, Tokyo dDepartment of Nursing, Ashikaga Institute of Technology, Ashikaga, Tochigi, Japan
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Harstad RK, Bowser MT. High-Speed Microdialysis-Capillary Electrophoresis Assays for Measuring Branched Chain Amino Acid Uptake in 3T3-L1 cells. Anal Chem 2016; 88:8115-22. [PMID: 27398773 DOI: 10.1021/acs.analchem.6b01846] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
We have developed a high-throughput microdialysis-capillary electrophoresis (MD-CE) assay for monitoring branched chain amino acid (BCAA) uptake/release dynamics in 3T3-L1 cells. BCAAs (i.e., isoleucine, leucine, and valine) and their downstream metabolites (i.e., alanine, glutamine, and glutamate) are important indicators of adipocyte lipogenesis. To perform an analysis, amino acids were sampled using microdialysis, fluorescently labeled in an online reaction, separated using CE, and detected using laser-induced fluorescence (LIF) in a sheath flow cuvette. Separation conditions were optimized for the resolution of the BCAAs isoleucine, leucine, and valine, as well as 13 other amino acids, including ornithine, alanine, glutamine, and glutamate. CE separations were performed in <30 s, and the temporal resolution of the online MD-CE assay was <60 s. Limits of detection (LOD) were 400, 200, and 100 nM for isoleucine, leucine, and valine, respectively. MD-CE dramatically improved throughput in comparison to traditional offline CE methods, allowing 8 replicates of 15 samples (i.e., 120 analyses) to be assayed in <120 min. The MD-CE assay was used to assess the metabolism dynamics of 3T3-L1 cells over time, confirming the utility of the assay.
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Affiliation(s)
- Rachel K Harstad
- Department of Chemistry, University of Minnesota 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Michael T Bowser
- Department of Chemistry, University of Minnesota 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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Denoroy L, Parrot S. Analysis of Amino Acids and Related Compounds by Capillary Electrophoresis. SEPARATION AND PURIFICATION REVIEWS 2016. [DOI: 10.1080/15422119.2016.1212378] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Rodrigues KT, Mekahli D, Tavares MFM, Van Schepdael A. Development and validation of a CE-MS method for the targeted assessment of amino acids in urine. Electrophoresis 2016; 37:1039-47. [PMID: 26826549 DOI: 10.1002/elps.201500534] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 01/22/2016] [Accepted: 01/24/2016] [Indexed: 12/14/2022]
Abstract
A CE-ESI-MS method was developed and validated for the separation and quantitative analysis of amino acids (AA) in urine. Experimental parameters related to the CE-MS interface, BGE, and mass spectrometer (MS) settings were optimized providing a good separation of 27 AA, including the isomers L-leucine, L-isoleucine, and L-alloisoleucine, in less than 30 min. The sheath liquid was composed by 0.50% formic acid in 60% (v,v) methanol-water delivered at a flow rate of 5 μL/min. The BGE consisted of 0.80 mol/L formic acid at pH 1.96 and 15% methanol. A pH stacking procedure was implemented to enhance sensitivity (a 12.5% NH4 OH solution was injected at 0.5 psi/9 s prior to samples injected at 0.6 psi/20 s). The proposed method was validated according to FDA and ICH protocols exhibiting acceptable parameters. Analytical curves presented coefficients of determination from 0.996 to 0.9997 (with large F statistics and low p-values). LODs and quantification ranged from 0.63 to 29 μmol/L and from 1.9 to 86 μmol/L, respectively. Practical repeatability was obtained for all AA with coefficients of variation better than 0.55% CV (migration time) and 1.7% CV (peak area ratios; methionine sulfone as internal standard). Recoveries of AA in spiked urine ranged from 92.0 to 123% with few exceptions. Moreover, a successful quantification of AA in pooled control and test urine samples, which compose a vesicoureteral reflux cohort, was achieved showing the potential applicability of the proposed method for targeted metabolomics studies using CE-ESI-MS with an Ion Trap as mass analyzer.
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Affiliation(s)
- Karina T Rodrigues
- Department of Pharmaceutical and Pharmacological Sciences, Pharmaceutical Analysis, KU Leuven-University of Leuven, Leuven, Belgium.,Institute of Chemistry, University of Sao Paulo, Sao Paulo, Brazil
| | - Djalila Mekahli
- Department of Development and Regeneration, Molecular and Cellular Signal Transduction, KU Leuven-University of Leuven, Leuven, Belgium.,Department of Pediatric Nephrology, University Hospitals Leuven, Leuven, Belgium
| | | | - Ann Van Schepdael
- Department of Pharmaceutical and Pharmacological Sciences, Pharmaceutical Analysis, KU Leuven-University of Leuven, Leuven, Belgium
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Abstract
PURPOSE OF REVIEW Numerous human studies have consistently demonstrated that concentrations of branched-chain amino acids (BCAAs) in plasma and urine are associated with insulin resistance and have the quality to predict diabetes development. However, it is not known how altered BCAA levels link to insulin action and diabetes. This review addresses some recent findings in BCAA metabolism and discusses their role as reporter molecules of insulin sensitivity and diabetes and their possible contribution to disease progression. RECENT FINDINGS Changes in plasma and urine levels result mainly from altered metabolism in tissues and recent studies have thus focused on organ-specific changes in BCAA handling using animal models and human tissue samples. A decreased mitochondrial oxidation has been demonstrated in peripheral tissues and that was shown to be associated with an increased inflammatory tone and changes in adipokine levels (adiponectin and leptin). These changes appear already before insulin resistance is established. Key findings demonstrating the discordance between changes in BCAA and insulin resistance are derived from studies using insulin sensitizers and from data collected in patients undergoing Roux-en-Y bypass bariatric surgery. Intermediates derived from BCAA breakdown rather than BCAA itself were recently proposed to contribute to the development of insulin resistance and studies now explore the biomarker qualities of these metabolites. SUMMARY Understanding the mechanisms and putative causalities in the alterations in BCAA levels as found in obesity, metabolic syndrome and diabetes is crucial for any intervention options but also for the use of BCAA and derivatives as biomarkers in clinical routine.
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