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Asakawa D, Saikusa K, Yoshida H, Han Z, Chen LC. Tuning the Internal Energy of Ions Produced by Atmospheric and High-Pressure Electrospray by Modulating the Gas Throughput into the First Vacuum Stage. Anal Chem 2024; 96:10748-10755. [PMID: 38877968 DOI: 10.1021/acs.analchem.4c01813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/03/2024]
Abstract
In a high-pressure environment, electrospray ionization (ESI) can be achieved without discharge between the emitter and the counter electrode, thus enabling the generation of gas-phase ions from liquid with high surface tension, such as pure water, which requires a high onset voltage for stable ESI. In this study, the ion dissociation during the transferring of ions/charged droplets from a superatmospheric pressure environment to vacuum has been systematically investigated using benzyl ammonium thermometer ions. The ion source pressure did not affect the internal energy distribution of ions, whereas the gas throughput into the first vacuum stage clearly influences the internal energy distribution of the ions. The increase in the gas throughput increased the density of molecules/atoms presented in ion transfer/focusing electrodes located in the first vacuum stage. As a result, the mean free path of ions in the first vacuum stage decreases, and the energy of ions decreases by decreasing the kinetic energy involved in each collision between ions and residue gas. The gas throughput into the first vacuum stage is found to describe the internal energy distribution of ions associated with the local conditions more quantitatively instead of using the measured pressure of the vacuum stage, which is different from the effective local pressure. This study also demonstrated the controlled dissociation of ions using the ion transfer settings of the instrument in combination with ion inlet tubes of different sizes.
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Affiliation(s)
- Daiki Asakawa
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8568, Japan
| | - Kazumi Saikusa
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8563, Japan
| | - Hajime Yoshida
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8563, Japan
| | - Zhongbao Han
- University of Yamanashi, Kofu, Yamanashi 400-0016, Japan
| | - Lee Chuin Chen
- University of Yamanashi, Kofu, Yamanashi 400-0016, Japan
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2
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Asakawa D, Yamamoto R, Hanari N, Saikusa K. Differences in the internal energies of ions in electrospray ionization mass spectrometers equipped with capillary-skimmer and capillary-RF lens interfaces. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2023; 15:6150-6158. [PMID: 37830393 DOI: 10.1039/d3ay01450a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/14/2023]
Abstract
Small metabolites are commonly analyzed using electrospray ionization mass spectrometry (ESI-MS). Although the protonated form of a compound of interest is typically the target ion in ESI-MS, the protonated forms of small metabolites occasionally undergo fragmentation during ion transmission from ambient conditions to vacuum conditions, hindering the unambiguous identification of analyte molecules. To estimate the fragmentation efficiency during ESI processes, the internal energy distribution of the ions (P(E)) must be evaluated. The common approach for the P(E) evaluation is the survival yield method, which uses thermometer ions. In this study, the P(E) of ions produced by an ESI source in a commercial triple quadrupole mass spectrometer equipped with a capillary-skimmer and capillary-RF lens interfaces was evaluated using benzyl ammonium thermometer ions. Furthermore, this study proposes the use of 3-(aminomethyl)indole and related compounds, which have the lowest Eapp values among the reported thermometer ions, to obtain P(E) values of the ions more accurately. Results showed that P(E) strongly depends on whether a capillary-skimmer interface or capillary-RF lens interface was used for ion transport to the vacuum. ESI-MS with a capillary-skimmer interface provided a considerably lower and narrower P(E) of ions than that with a capillary-RF lens interface, thereby producing intact protonated molecules without significant fragmentation of most small metabolites. However, ESI-MS equipped with capillary-RF lens interfaces provided a higher efficiency of ion transmission than ESI-MS equipped with a capillary-skimmer interface, allowing for highly sensitive analysis of metabolites.
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Affiliation(s)
- Daiki Asakawa
- National Institute of Advanced Industrial Science and Technology (AIST), National Metrology Institute of Japan (NMIJ), Tsukuba, Japan.
| | | | - Nobuyasu Hanari
- National Institute of Advanced Industrial Science and Technology (AIST), National Metrology Institute of Japan (NMIJ), Tsukuba, Japan.
| | - Kazumi Saikusa
- National Institute of Advanced Industrial Science and Technology (AIST), National Metrology Institute of Japan (NMIJ), Tsukuba, Japan.
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3
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Walther R, Kinzig M, Zamponi A, Sörgel F, Scherf-Clavel O, Holzgrabe U. Identification of low-level impurities in drug prototypes of carbocisteine by means of liquid chromatography-high-resolution mass spectrometry and general unknown comparative screening. J Chromatogr A 2023; 1706:464269. [PMID: 37586140 DOI: 10.1016/j.chroma.2023.464269] [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: 03/30/2023] [Revised: 07/06/2023] [Accepted: 08/01/2023] [Indexed: 08/18/2023]
Abstract
High-resolution tandem quadrupole time-of-flight mass analysers enable new automated workflows for untargeted data evaluation of complex samples like drug products. An example of such procedure is the so-called general unknown comparative screening (GUCS), which is used for software-assisted, automated identification of components that are only present in a sample and not in a reference. The GUCS approach has been employed for the first time to detect both degradation products and reaction products in drug products. Two different carbocisteine containing syrup prototypes - one with sucrose and the other with artificial sweeteners - were selected as examples after nine months of storage at 40 °C and 75% relative humidity. The samples were analysed chromatographically using a Coresep SB mixed-mode column and high-resolution MS and MS/MS data were recorded in information dependant acquisition mode on a Sciex X500R quadrupole time-of-flight mass spectrometer. Data analysis was considerably facilitated using the corresponding placebo formulation as reference samples. With the GUCS approach two hitherto unknown degradation products of carbocisteine, i.e. the carbocisteine lactam of the sulfoxides and the disulfide between l-cysteine and thioglycolic acid, were detected at low concentrations in both of the syrup formulations. The presumed structures were confirmed by in silico analysis of the fragment spectra and high-resolution LC-MS experiments with reference substances. Two additional impurities were found in the sucrose-containing sample and identified as the N-glycosides of carbocisteine and its lactam, respectively, using binary mixtures with a 13C-labelled monosaccharide.
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Affiliation(s)
- Rasmus Walther
- Institute for Pharmacy and Food Chemistry, University of Wuerzburg, Am Hubland, Würzburg 97074, Germany
| | - Martina Kinzig
- Institute for Biomedical and Pharmaceutical Research, Heroldsberg 90562, Germany
| | - Annette Zamponi
- Global Development Center, A. Nattermann & Cie. GmbH - a Sanofi Company, Köln 50829, Germany
| | - Fritz Sörgel
- Institute for Biomedical and Pharmaceutical Research, Heroldsberg 90562, Germany
| | - Oliver Scherf-Clavel
- Institute for Pharmacy and Food Chemistry, University of Wuerzburg, Am Hubland, Würzburg 97074, Germany.
| | - Ulrike Holzgrabe
- Institute for Pharmacy and Food Chemistry, University of Wuerzburg, Am Hubland, Würzburg 97074, Germany.
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4
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Chen L, Pan H, Zhai G, Luo Q, Li Y, Fang C, Shi F. Widespread occurrence of in-source fragmentation in the analysis of natural compounds by liquid chromatography-electrospray ionization mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2023; 37:e9519. [PMID: 37038638 DOI: 10.1002/rcm.9519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/14/2023] [Accepted: 04/03/2023] [Indexed: 05/17/2023]
Abstract
RATIONALE The in-source fragmentation (ISF) of analyte or co-eluting substances produces unintentional fragment ions, which hampers identification and quantification by liquid chromatography-mass spectrometry (LC/MS). Natural compounds derived from plants also contain fragile moieties that may undergo ISF. However, the characteristics of ISF of natural compounds in LC/MS are still unclear. METHODS The ISF behavior of 214 natural compounds was assayed in LC with Q/orbitrap MS in electrospray ionization (ESI) mode and the extent of ISF was evaluated. RESULTS Up to 82% of tested compounds underwent ISF and half of the tested natural compounds that contain more than one fragile moiety underwent successive and severe ISF to generate serial structurally related ISF products. The major ISF-altering moieties for natural compounds were hydroxyl, lactone, glycosyl and ether, resulting in neutral loss of H2 O or CO, deglycosylation or cleavage of ether bond, respectively. Some compounds such as terpenoids underwent severe ISF and less than 1% parent form can be observed. For natural compounds, ISF products with similar structures are more likely to cause interference in analysis because the ISF products may share identical mass-to-charge ratio and similar MS2 fragmentation patterns with precursor ions of the homologs in plants. Furthermore, severe ISF may cause a false negative in the identification of the parent form. CONCLUSIONS In summary, ISF was a highly frequent phenomenon for analysis of natural compounds by LC/ESI-MS, and extensive and successive ISF of natural products may cause misannotation and misidentification with homologs in plants. The study should raise awareness of ISF interference during the analysis of natural compounds.
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Affiliation(s)
- Lin Chen
- Key Laboratory of Basic Pharmacology of Ministry of Education & Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, China
| | - Hong Pan
- Department of Clinical Pharmacy, School of Pharmacy, Zunyi Medical University, Zunyi, China
| | - Guohong Zhai
- Key Laboratory of Basic Pharmacology of Ministry of Education & Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, China
| | - Qi Luo
- Key Laboratory of Basic Pharmacology of Ministry of Education & Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, China
| | - Yi Li
- Key Laboratory of Basic Pharmacology of Ministry of Education & Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, China
| | - Chao Fang
- Key Laboratory of Basic Pharmacology of Ministry of Education & Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, China
- Department of Pharmacology and Chemical Biology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Fuguo Shi
- Key Laboratory of Basic Pharmacology of Ministry of Education & Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, China
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5
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Wan D, Wang FQ, Xie J, Chen L, Zhou XL. Design, Synthesis, and Biological Activity of Donepezil: Aromatic Amine Hybrids as Anti-Alzheimerss Drugs. ACS OMEGA 2023; 8:21802-21812. [PMID: 37360465 PMCID: PMC10286275 DOI: 10.1021/acsomega.3c01427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 05/25/2023] [Indexed: 06/28/2023]
Abstract
In this study, benzylpiperidine, the active group of donepezil (DNP), was connected with the neurotransmitter phenylethylamine by square amide, in which the fat chain of phenylethylamine was reduced and the benzene rings were substituted. A series of multifunctional hybrid compounds, including DNP-aniline hybrids (1-8), DNP-benzylamine hybrids (9-14), and DNP-phenylethylamine hybrids (15-21) were obtained and their cholinesterase inhibitory activity and neuroprotection of the SH-SY5Y cell line were determined. Results showed that compound 3 exhibited excellent acetylcholinesterase inhibitory activity with an IC50 value of 4.4 μM, higher than that of positive control DNP and significant neuroprotective effects against H2O2-induced oxidative damage in SH-SY5Y cells with 80.11% viability rate at 12.5 μM, much higher than that of the model group (viability rate = 53.1%). The mechanism of action of compound 3 was elucidated by molecular docking, reactive oxygen species (ROS), and immunofluorescence analysis. The results suggest that compound 3 could be further explored as a lead compound for the treatment of Alzheimer's disease. In addition, molecular docking research indicated that the square amide group formed strong interactions with the target protein. Based on the above analysis, we believe that square amide could be an interesting construction unit in anti-AD agents.
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Affiliation(s)
- Dan Wan
- School
of Life Science and Engineering, Southwest
Jiaotong University, Chengdu 610031, Sichuan, P.R. China
| | - Feng-Qin Wang
- School
of Life Science and Engineering, Southwest
Jiaotong University, Chengdu 610031, Sichuan, P.R. China
| | - Jiang Xie
- Affiliated
Hospital of Southwest Jiaotong University & The Third People Hospital
of Chengdu, Chengdu 610031, Sichuan, P.R. China
| | - Lin Chen
- School
of Life Science and Engineering, Southwest
Jiaotong University, Chengdu 610031, Sichuan, P.R. China
| | - Xian-Li Zhou
- School
of Life Science and Engineering, Southwest
Jiaotong University, Chengdu 610031, Sichuan, P.R. China
- Affiliated
Hospital of Southwest Jiaotong University & The Third People Hospital
of Chengdu, Chengdu 610031, Sichuan, P.R. China
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6
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Chen YN, Shen XY, Yu Y, Xue CY, Zhou YL, Zhang XX. In-source fragmentation of nucleosides in electrospray ionization towards more sensitive and accurate nucleoside analysis. Analyst 2023; 148:1500-1506. [PMID: 36883656 DOI: 10.1039/d3an00047h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
Nucleosides have been found to suffer in-source fragmentation (ISF) in electrospray ionization mass spectrometry, which leads to reduced sensitivity and ambiguous identification. In this work, a combination of theoretical calculations and nuclear magnetic resonance analysis revealed the key role of protonation at N3 near the glycosidic bond during ISF. Therefore, an ultrasensitive liquid chromatography-tandem mass spectrometry system for 5-formylcytosine detection was developed with 300 fold signal enhancement. Also, we established a MS1-only platform for nucleoside profiling and successfully identified sixteen nucleosides in the total RNA of MCF-7 cells. Taking ISF into account, we can realize analysis with higher sensitivity and less ambiguity, not only for nucleosides, but for other molecules with similar protonation and fragmentation behaviors.
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Affiliation(s)
- Yu-Nan Chen
- Beijing National Laboratory for Molecular Sciences (BNLMS), MOE Key Laboratory of Bioorganic Chemistry and Molecular Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing, China.
| | - Xu-Yang Shen
- Beijing National Laboratory for Molecular Sciences (BNLMS), MOE Key Laboratory of Bioorganic Chemistry and Molecular Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing, China.
| | - Yue Yu
- Institute of Biotechnology Development, Qilu Pharmaceutical, Jinan, China
| | - Chen-Yu Xue
- Key Laboratory of Forensic Toxicology, Ministry of Public Security, Beijing, China
| | - Ying-Lin Zhou
- Beijing National Laboratory for Molecular Sciences (BNLMS), MOE Key Laboratory of Bioorganic Chemistry and Molecular Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing, China.
| | - Xin-Xiang Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS), MOE Key Laboratory of Bioorganic Chemistry and Molecular Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing, China.
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7
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Asakawa D, Todoroki K, Mizuno H. Fragmentation of Protonated Histamine and Histidine by Electrospray Ionization In-Source Collision-Induced Dissociation. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:1716-1722. [PMID: 35973087 DOI: 10.1021/jasms.2c00140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Electrospray ionization (ESI) generally produces intact gas-phase ions without extensive fragmentation; however, for histamine and histidine, ESI provides fragment ions through in-source collision-induced dissociation (CID). In this study, we investigated the fragmentation of these compounds both experimentally and using density functional theory calculations. We found that histamine undergoes protonation with subsequent NH3 loss by ESI in-source CID. The corresponding fragmentation mainly produces bicyclo and spiro compounds. In contrast, the ESI in-source CID of protonated histidine preferentially results in H2O loss rather than NH3 loss. However, the corresponding fragment ion is not observed in the ESI mass spectrum of histidine, because it undergoes further CO loss within 100 ps. Consequently, protonated histidine produces a fragment ion arising from a 46 Da loss, which corresponds to the masses of H2O and CO, by ESI in-source CID. The fragment ion yields of histamine and histidine produced by ESI in-source CID are then estimated from the dissociation rate constant and internal energy of the analyte ion, respectively. The dissociation rate constant and internal energy of the analyte ion were determined by double-hybrid density functional theory calculations and the survival yield method using benzylpyridinium thermometer ions, respectively. Because intense fragment ion signals are present in the ESI mass spectrum, the analysis of the fragment ions produced by ESI in-source CID facilitates the identification of metabolites originating from aromatic amino acids, such as histamine.
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Affiliation(s)
- Daiki Asakawa
- National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
| | - Kenichiro Todoroki
- School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan
| | - Hajime Mizuno
- School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan
- Faculty of Pharmacy, Meijo University, Nagoya, Aichi 468-8502, Japan
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8
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Asakawa D, Saikusa K. Characterization of the Internal Energy of Ions Produced by Electrospray Ionization Using Substituted Benzyl Ammonium Thermometer Ions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:1548-1554. [PMID: 35853154 DOI: 10.1021/jasms.2c00116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We propose the use of substituted benzyl ammonium species as thermometer ions to characterize the internal energy distribution of the ions produced by electrospray ionization (ESI). Crucially, we found that the activation of the benzyl ammonium species preferentially provided a benzyl cation via N-Cα bond cleavage. In addition, calculations at the CCSD(T)/cc-PVTZ//M06-2X-D3/6-311++G(d,p) level of theory revealed that the threshold energies of fragmentation of the tested model ions ranged from 86 to 192 kJ mol-1, significantly lower than those of conventional 4-substituted benzylpyridinium thermometer ions. Thus, the substituted benzyl ammoniums are suitable for the characterization of the ESI process under typical experimental conditions. Further, the internal energies of the ions were found to depend on the radiofrequency voltage of the ion funnel, which is used to increase the transport efficiency of the ions from atmospheric to vacuum conditions. Our reported method will aid the determination of the optimum ion-funnel radiofrequency voltage for the analysis of small molecules such as metabolites. Furthermore, benzyl ammoniums are commercially available, which will facilitate the routine and widespread measurement of the internal energy distributions of ions.
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Affiliation(s)
- Daiki Asakawa
- Research Institute for Measurement and Analytical Instrumentation, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Kazumi Saikusa
- Research Institute for Material and Chemical Measurement, National Institute of Advanced Industrial Science and Technology (AIST), National Metrology Institute of Japan (NMIJ), Tsukuba Central 3, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563, Japan
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9
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Duan QL, Shi HW, Tan L, Liu Z, Huang Q, Shen W, Cao L, Lee HK, Tang S. Ultrahigh-Performance Supercritical Fluid Chromatography and Detection of Multiple Biogenic Amines in Gentamicin Sulfate: Method Development Using Computer-Assisted Modeling. Anal Chem 2022; 94:7229-7237. [PMID: 35532756 DOI: 10.1021/acs.analchem.2c00325] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In order to solve the problem of difficult separation of various biogenic amines (BAs), which have similar structures or very different polarities, in gentamicin, by conventional liquid chromatography, a new ultrahigh-performance supercritical fluid chromatography (UHPSFC) method was developed. In this method, 10 BAs were derivatized precolumn using dansyl chloride and separated using a UHPSFC system. By computational simulation, complete separation of 10 BAs was successfully achieved. Detection was performed using a photodiode array (PDA) and single-quadrupole mass spectrometry (MS) together with electrospray ionization (ESI). A wide linear range (10-2500 ng/mL) was achieved, with the limits of detection (LODs) between 1.2 and 10.0 ng/mL and the limits of quantification (LOQs) between 5.0 and 25.0 ng/mL. Apart from high sensitivity, this UHPSFC-PDA/ESI-MS detection method also displayed high accuracy, the matrix effect was reduced by an appreciable extent, and the recovery rates of the 10 BAs were between 84.1 and 117.1%. For comparison, high-performance liquid chromatography-tandem mass spectrometry (MS/MS) was also used for the detection of underivatized BAs in gentamicin, showing good linearity and high sensitivity (LODs from 0.05 to 1.00 ng/mL and LOQs from 1.00 to 12.50 ng/mL) for all BAs except for spermine and spermidine. Although single-quadrupole MS is inferior to MS/MS in terms of sensitivity, the UHPSFC method could detect more BAs. It also achieved the quantification limits required for impurity determination, demonstrating a potential strategy to offer a map overview of possible BA presence in fermentation antibiotics.
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Affiliation(s)
- Qiao-Lian Duan
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210046, Jiangsu Province, P. R. China.,Jiangsu Institute for Food and Drug Control, Nanjing 210019, Jiangsu Province, P. R. China
| | - Hai-Wei Shi
- Jiangsu Institute for Food and Drug Control, Nanjing 210019, Jiangsu Province, P. R. China
| | - Li Tan
- Jiangsu Institute for Food and Drug Control, Nanjing 210019, Jiangsu Province, P. R. China
| | - Zhen Liu
- Nanjing Institute for Food and Drug Control, Nanjing, Jiangsu Province 211198, P. R. China
| | - Qing Huang
- Jiangsu Institute for Food and Drug Control, Nanjing 210019, Jiangsu Province, P. R. China
| | - Wei Shen
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, Jiangsu Province, P. R. China
| | - Ling Cao
- Jiangsu Institute for Food and Drug Control, Nanjing 210019, Jiangsu Province, P. R. China
| | - Hian Kee Lee
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Sheng Tang
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, Jiangsu Province, P. R. China
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10
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Bonetti JL, Samanipour S, van Asten AC. Utilization of Machine Learning for the Differentiation of Positional NPS Isomers with Direct Analysis in Real Time Mass Spectrometry. Anal Chem 2022; 94:5029-5040. [PMID: 35297608 PMCID: PMC8968871 DOI: 10.1021/acs.analchem.1c04985] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
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The differentiation
of positional isomers is a well established
analytical challenge for forensic laboratories. As more novel psychoactive
substances (NPSs) are introduced to the illicit drug market, robust
yet efficient methods of isomer identification are needed. Although
current literature suggests that Direct Analysis in Real Time–Time-of-Flight
mass spectrometry (DART-ToF) with in-source collision induced dissociation
(is-CID) can be used to differentiate positional isomers, it is currently
unclear whether this capability extends to positional isomers whose
only structural difference is the precise location of a single substitution
on an aromatic ring. The aim of this work was to determine whether
chemometric analysis of DART-ToF data could offer forensic laboratories
an alternative rapid and robust method of differentiating NPS positional
ring isomers. To test the feasibility of this technique, three positional
isomer sets (fluoroamphetamine, fluoromethamphetamine, and methylmethcathinone)
were analyzed. Using a linear rail for consistent sample introduction,
the three isomers of each type were analyzed 96 times over an eight-week
timespan. The classification methods investigated included a univariate
approach, the Welch t test at each included ion;
a multivariate approach, linear discriminant analysis; and a machine
learning approach, the Random Forest classifier. For each method,
multiple validation techniques were used including restricting the
classifier to data that was only generated on one day. Of these classification
methods, the Random Forest algorithm was ultimately the most accurate
and robust, consistently achieving out-of-bag error rates below 5%.
At an inconclusive rate of approximately 5%, a success rate of 100%
was obtained for isomer identification when applied to a randomly
selected test set. The model was further tested with data acquired
as a part of a different batch. The highest classification success
rate was 93.9%, and error rates under 5% were consistently achieved.
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Affiliation(s)
- Jennifer L Bonetti
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, P.O. Box 94157, Amsterdam 1090 GD, The Netherlands.,Virginia Department of Forensic Science, Norfolk, Virginia 23606, United States
| | - Saer Samanipour
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, P.O. Box 94157, Amsterdam 1090 GD, The Netherlands
| | - Arian C van Asten
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, P.O. Box 94157, Amsterdam 1090 GD, The Netherlands.,Co van Ledden Hulsebosch Center (CLHC), Amsterdam Center for Forensic Science and Medicine, 1098 XH Amsterdam, The Netherlands
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11
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Asakawa D, Saikusa K. Fragmentation efficiency of phenethylamines in electrospray ionization source estimated by theoretical chemistry calculation. JOURNAL OF MASS SPECTROMETRY : JMS 2021; 57:e4802. [PMID: 34929756 DOI: 10.1002/jms.4802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 11/08/2021] [Accepted: 11/25/2021] [Indexed: 06/14/2023]
Abstract
Small molecules with polar functional groups, including substituted phenethylamines, are commonly analyzed by liquid chromatography-mass spectrometry (LC-MS) with electrospray ionization (ESI). Analyte molecules are mostly detected in protonated and cation-adducted forms through positive-ion electrospray ionization-mass spectrometry (ESI-MS). However, the ESI of substituted phenethylamines commonly provides an intense signal of fragment ions by ESI in-source collision-induced dissociation (IS-CID), which hinders the unambiguous identification of phenethylamines. This phenomenon was approximated as a unimolecular dissociation model, and the dissociation efficiency was evaluated by various quantum chemistry calculations to determine the ESI IS-CID efficiency. The calculated results were consistent with the experimental data, when the dissociation threshold energy of phenethylamines was calculated using the post-Hartree-Fock (post-HF) method, CCSD(t)/cc-pVTZ//MP2(full)/6-311++G(d,p). In contrast to post-HF methods, the utilization of density functional theory calculations with a suitable functional is recognized as an accurate and competitive low-cost approach. In particular, ωB97-XD, M06-2X-D3, and recently developed Minnesota functionals, such as M11, MN12-SX, and MN15, provided reliable results, as in the case of the post-HF method. The results obtained by the recently developed double hybrid functionals, DSD-PEBP86-D3(BJ), PBE0-DH, and PBE-QIDH, were also reliable. The consideration of ESI IS-CID can facilitate the identification of analyte molecules because most phenethylamines, except for N-methylated analogs, provide an intense signal in the ESI mass spectrum.
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Affiliation(s)
- Daiki Asakawa
- Research Institute for Measurement and Analytical Instrumentation, National Institute of Advanced Industrial Science and Technology, National Metrology Institute of Japan, Tsukuba, Japan
| | - Kazumi Saikusa
- Research Institute for Material and Chemical Measurement, National Institute of Advanced Industrial Science and Technology, National Metrology Institute of Japan, Tsukuba, Japan
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12
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Asakawa D, Sugiyama E, Mizuno H, Todoroki K. Study of Substituted Phenethylamine Fragmentation Induced by Electrospray Ionization Mass Spectrometry and Its Application for Highly Sensitive Analysis of Neurotransmitters in Biological Samples. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:2144-2152. [PMID: 34293862 DOI: 10.1021/jasms.1c00173] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Although liquid chromatography-tandem mass spectrometry (LC-MS/MS) equipped with electrospray ionization (ESI) is widely employed for metabolite analysis, substituted phenethylamines commonly undergo fragmentation during ESI in-source collision-induced dissociation (CID). Unexpected fragmentation hampers not only unambiguous identification but also accurate metabolite quantification. ESI in-source CID induces N-Cα bond dissociation in substituted phenethylamines lacking a β-hydroxy group to produce fragment ions with a spiro[2.5]octadienylium motif. In contrast, phenethylamines with a β-hydroxy group generate substituted 2-phenylaziridium through ESI in-source CID-induced H2O loss. The fragment ion yield produced by ESI in-source CID can be estimated by the dissociation rate constant and internal energy of the analyte ion, determined by employing density functional theory calculations and the survival yield method using a thermometer ion, respectively. Fragmentation is strongly enhanced by the presence of an β-hydroxy group, whereas N-methylation suppresses fragmentation. In particular, octopamine and noradrenaline, which contain an β-hydroxy and primary amine groups, produce more intense fragment ion signals than protonated molecules. Regarding the quantitative analysis of phenethylamines present in the mouse brain, the noradrenaline fragment ion used as the precursor in multiple reaction monitoring (MRM) provided a higher signal-to-noise ratio in the resulting spectra than protonated noradrenaline. The present method allows for the quantitative analysis of substituted phenethylamines with high sensitivity.
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Affiliation(s)
- Daiki Asakawa
- National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Eiji Sugiyama
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Hajime Mizuno
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| | - Kenichiro Todoroki
- School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
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Asakawa D, Mizuno H, Sugiyama E, Todoroki K. Fragmentation study of tryptophan-derived metabolites induced by electrospray ionization mass spectrometry for highly sensitive analysis. Analyst 2021; 146:2292-2300. [DOI: 10.1039/d0an02069a] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
ESI of tryptophan-derived metabolites produced an intense signal of fragment ion with a spiro[cyclopropane-indolium] backbone. The use of corresponding fragment ions for the precursor of MRM transitions could improve the detection limit.
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Affiliation(s)
- Daiki Asakawa
- National Institute of Advanced Industrial Science and Technology
- Tsukuba
- Japan
| | - Hajime Mizuno
- School of Pharmaceutical Sciences
- University of Shizuoka
- Shizuoka 422-8526
- Japan
| | - Eiji Sugiyama
- School of Pharmaceutical Sciences
- University of Shizuoka
- Shizuoka 422-8526
- Japan
| | - Kenichiro Todoroki
- School of Pharmaceutical Sciences
- University of Shizuoka
- Shizuoka 422-8526
- Japan
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