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Parsha S, Kumar YR, Ravichander M. LC–MS/MS and NMR Characterization of Key Impurities in Linagliptin and Pramipexole. J LIQ CHROMATOGR R T 2015. [DOI: 10.1080/10826076.2015.1087861] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Swetha Parsha
- Department of Analytical Research and Development, Integrated Product Development, Dr. Reddy’s Laboratories, Hyderabad, India
- Department of Chemistry, Jawaharlal Nehru Technological University, Hyderabad, India
| | - Y. Ravindra Kumar
- Department of Analytical Research and Development, Integrated Product Development, Dr. Reddy’s Laboratories, Hyderabad, India
| | - M. Ravichander
- Department of Chemistry, Mahatma Gandhi Institute of Technology, Hyderabad, India
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2
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Xue Y, Gu X, Wang Y, Yan C. Recent advances on capillary columns, detectors, and two-dimensional separations in capillary electrochromatography. Electrophoresis 2014; 36:124-34. [PMID: 25223262 DOI: 10.1002/elps.201400312] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 08/24/2014] [Accepted: 08/25/2014] [Indexed: 02/01/2023]
Abstract
As a typical miniaturized analytical technique, CEC has attracted much attention because of its low sample and solvent consumption, high efficiency, high selectivity, high resolution, and fast speed. In this review, we mainly cover the development of capillary columns and detection techniques in the CEC since 2009. Herein, three types of capillary columns, namely, open-tubular capillary columns, monolithic columns and packed columns, and several types of detectors are reviewed in detail. Moreover, a 2D separation system based on CEC is also reported.
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Affiliation(s)
- Yun Xue
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai, P. R. China
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3
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Maggio RM, Calvo NL, Vignaduzzo SE, Kaufman TS. Pharmaceutical impurities and degradation products: uses and applications of NMR techniques. J Pharm Biomed Anal 2014; 101:102-22. [PMID: 24853620 DOI: 10.1016/j.jpba.2014.04.016] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 04/11/2014] [Accepted: 04/12/2014] [Indexed: 11/29/2022]
Abstract
Current standards and regulations demand the pharmaceutical industry not only to produce highly pure drug substances, but to achieve a thorough understanding of the impurities accompanying their manufactured drug substances and products. These challenges have become important goals of process chemistry and have steadily stimulated the search of impurities after accelerated or forced degradation procedures. As a result, impurity profiling is one of the most attractive, active and relevant fields of modern pharmaceutical analysis. This activity includes the identification, structural elucidation and quantitative determination of impurities and degradation products in bulk drugs and their pharmaceutical formulations. Nuclear magnetic resonance (NMR) spectroscopy has evolved into an irreplaceable approach for pharmaceutical quality assessment, currently playing a critical role in unequivocal structure identification as well as structural confirmation (qualitative detection), enabling the understanding of the underlying mechanisms of the formation of process and/or degradation impurities. NMR is able to provide qualitative information without the need of standards of the unknown compounds and multiple components can be quantified in a complex sample without previous separation. When coupled to separative techniques, the resulting hyphenated methodologies enhance the analytical power of this spectroscopy to previously unknown levels. As a result, and by enabling the implementation of rational decisions regarding the identity and level of impurities, NMR contributes to the goal of making better and safer medicines. Herein are discussed the applications of NMR spectroscopy and its hyphenated derivate techniques to the study of a wide range pharmaceutical impurities. Details on the advantages and disadvantages of the methodology and well as specific challenges with regards to the different analytical problems are also presented.
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Affiliation(s)
- Rubén M Maggio
- Instituto de Química Rosario (IQUIR, CONICET-UNR) and Área Análisis de Medicamentos, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, Rosario S2002LRK, Argentina
| | - Natalia L Calvo
- Instituto de Química Rosario (IQUIR, CONICET-UNR) and Área Análisis de Medicamentos, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, Rosario S2002LRK, Argentina
| | - Silvana E Vignaduzzo
- Instituto de Química Rosario (IQUIR, CONICET-UNR) and Área Análisis de Medicamentos, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, Rosario S2002LRK, Argentina
| | - Teodoro S Kaufman
- Instituto de Química Rosario (IQUIR, CONICET-UNR) and Área Análisis de Medicamentos, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, Rosario S2002LRK, Argentina.
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4
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Lin Z, Pang J, Huang H, Zhang L, Chen G. [Recent advances in capillary electrochromatography and its coupling techniques]. Se Pu 2010; 28:273-83. [PMID: 20549979 DOI: 10.3724/sp.j.1123.2010.00273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
As a novel micro-separation technique, capillary electrochromatography (CEC) has the merits of high efficiency, high selectivity, high resolution and rapid analysis. However, the small-volume injection manipulated in capillary dimensions poses a great challenge for detectors in achieving high sensitivity. Currently, one of the major researches into CEC involves the development of some sensitive detection modes. The general introduction, which includes the historical perspectives and the principles of CEC, is briefly described. The recent advances about CEC coupled with various detectors and its applications in the separation of complex samples are summarized. A total of 141 references are reviewed.
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Affiliation(s)
- Zian Lin
- Key Laboratory of Analysis and Detection Technology for Food Safety of Ministry of Education, College of Chemistry & Chemical Engineering, Fuzhou University, Fuzhou 350002, China.
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5
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Liu S, Lin X, Zhang X, Lü H, Xie Z. Off-Column Amperometric Detection for Pressurized Capillary Electrochromatography. Chromatographia 2010. [DOI: 10.1365/s10337-010-1529-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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6
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Abstract
Although there are many publications related to technological or methodological developments of CEC, few focus on the analysis of natural products, especially phytochemical bioactive compounds. This review summarized the application of CEC in the analysis of phytochemical bioactive components, including flavonoids, nucleosides, steroids, lignans, quinones and coumarins, as well as fingerprint analysis of herbs. The strategies for optimization of CEC conditions and detection were also discussed.
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Affiliation(s)
- Feng-qing Yang
- Department of Pharmaceutics, College of Chemistry and Chemical Engineering, Chongqing University, Chongqing, P. R. China
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7
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Preparation and evaluation of a neutral methacrylate-based monolithic column for hydrophilic interaction stationary phase by pressurized capillary electrochromatography. J Chromatogr A 2009; 1216:4611-7. [DOI: 10.1016/j.chroma.2009.03.057] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2008] [Revised: 01/05/2009] [Accepted: 03/20/2009] [Indexed: 11/20/2022]
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8
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Tanret I, Mangelings D, Vander Heyden Y. Pressure-assisted CEC versus CEC using methacrylate-based monolithic columns: influence of the polymerization-mixture composition. Electrophoresis 2009; 29:4463-74. [PMID: 19035401 DOI: 10.1002/elps.200800296] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Pressure-assisted CEC (pCEC) can either be performed on a CE instrument by adding pressure at the column inlet, or by applying voltage on a capillary liquid chromatography system. This study investigates the pressure's added value in pCEC using an LC instrument as well as the influence of the polymerization-mixture composition on monolithic columns in such experimental circumstances. Two factors of the polymerization mixture, which is used to prepare the monolithic capillary columns, were varied according to an experimental design approach: the pore-forming solvent/total monomer ratio and the pore-forming solvents composition. Initially, the effect of the resulting stationary phase on the elution behavior of mainly pharmaceutical compounds was studied. Four responses were used to evaluate the effects on the chromatography: retention time, retention factor, peak asymmetry and number of theoretical plates. After processing the results, the stationary phase composition with the best chromatographic behavior was determined and tested. The advantageous properties of this stationary phase compared with the design center-point column were demonstrated. Secondly, the results of these pCEC experiments were compared with those generated in an identical experimental setup previously performed using CEC. Chromatographic conditions were chosen so that the center-point column showed similar retention in CEC and pCEC. The expected advantage (faster analysis) and drawback (decreased efficiency) of pCEC in the analysis of pharmaceuticals was evaluated. Analysis time and efficiency were both found to depend greatly on the porosity of the column. The conclusion of this comparison is that pCEC did not have a significant added value to CEC. However, this was mainly due to the instrument's limitation of the pressure-driven flow over the column. A clear benefit of the pCEC setup was apparatus-related, i.e. the presence of a loop injection system on the pCEC instrument, which avoids the injection problems that were occasionally observed in CEC.
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Affiliation(s)
- Indiana Tanret
- Department of Analytical Chemistry and Pharmaceutical Technology, Pharmaceutical Institute, Vrije Universiteit Brussel-VUB, Brussels, Belgium
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9
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Qu QS, Wang S, Mangelings D, Wang CY, Yang GJ, Hu XY, Yan C. Monolithic silica xerogel capillary column for separations in capillary LC and pressurized CEC. Electrophoresis 2009; 30:1071-6. [DOI: 10.1002/elps.200800245] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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10
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Lin Z, Xie Z. Direct determination of amino acids by pressurized capillary electrochromatography with chemiluminescence detection. J Sep Sci 2008; 31:2852-9. [DOI: 10.1002/jssc.200800138] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abstract
Capillary electrochromatography (CEC) is a micro-separation technique that combines the advantages of capillary zone electrophoresis with those of high-performance liquid chromatography. Accordingly, it has attracted extensive attention over the last decade. Among the stationary phases for CEC, monolithic stationary phase has been regarded as the most suitable stationary phase for CEC because of its simple preparation, the elimination of frits, and its excellent performance. In this chapter, procedures for preparing CEC monolithic columns with an improved configuration, in which there are stationary phases at both sides of detection window and no stationary phase at detection window, are presented. The separation of acidic and basic compounds on such monolithic columns is used as an example to demonstrate CEC separation protocol. Additionally, an on-line concentration technique in CEC is presented. As a result of the coexistence of stationary phase and electric field in a CEC column, it is possible to employ chromatographic zone sharpening and field-amplified sample stacking effects simultaneously to improve CEC detection sensitivity.
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12
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Lu M, Zhang L, Feng Q, Xia S, Chi Y, Tong P, Chen G. Pressure-assisted capillary electrochromatography with electrospray ionization-mass spectrometry based on silica-based monolithic column for rapid analysis of narcotics. Electrophoresis 2008; 29:936-43. [DOI: 10.1002/elps.200700653] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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13
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Lin Z, Lin J, Wu X, Lin X, Xie Z. Evaluation of band broadening in chemiluminescence detection coupled to pressurized capillary electrochromatography with an off-column coaxial flow interface. Electrophoresis 2008; 29:401-9. [DOI: 10.1002/elps.200700327] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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14
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Lin Z, Wu X, Lin X, Xie Z. End-column chemiluminescence detection for pressurized capillary electrochromatographic analysis of norepinephrine and epinephrine. J Chromatogr A 2007; 1170:118-21. [PMID: 17905257 DOI: 10.1016/j.chroma.2007.09.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2007] [Revised: 09/02/2007] [Accepted: 09/11/2007] [Indexed: 11/16/2022]
Abstract
A simple and convenient end-column chemiluminescence (CL) detection coupled to pressurized capillary electrochromatography (pCEC) was described. Luminol and N-(4-aminobutyl)-N-ethylisoluminol (ABEI) were adopted as mode compounds to evaluate the feasibility of end-column reactor. Detailed analysis of ABEI revealed that the high sensitivity could be obtained with the reactor. Furthermore, determination of norepinephrine (NE) and epinephrine (EP), which were labeled with ABEI, was accomplished by using the end-column pCEC-CL detection based on ABEI-potassium ferricyanide-alkaline medium CL reaction system. Under the optimum conditions, the detection limit (S/N=3) of NE and EP was 0.08 microM and 0.06 microM, respectively. The proposed method has also been successfully applied to the analysis of adrenaline hydrochloride injection sample.
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Affiliation(s)
- Zian Lin
- Department of Chemistry, Fuzhou University, Fuzhou 350002, China
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15
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Ye F, Li S, Zhao S. Development of a new C14 monolithic silica column containing embedded polar groups for pressurized capillary electrochromatography. J Sep Sci 2007; 30:3027-34. [DOI: 10.1002/jssc.200700316] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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16
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Liu S, Zhang X, Lin X, Wu X, Fu F, Xie Z. Development of a new method for analysis of Sudan dyes by pressurized CEC with amperometric detection. Electrophoresis 2007; 28:1696-703. [PMID: 17465422 DOI: 10.1002/elps.200600486] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A new analytical method, pressurized CEC (pCEC) with amperometric detection (AD) using 1.5 microm RP nonporous silica packed columns has been developed for the rapid separation and determination of four Sudan dyes in hot chilli. The influence of several experimental parameters on the retention behavior has been investigated. The electrochemical oxidation of Sudans I-IV separated by pCEC can be reliably monitored with a carbon electrode at +0.95 V (vs. Ag/AgCl). Fast and efficient separation of the analytes was achieved within 7 min by pCEC under the optimum conditions with an ACN/water (95:5%) mobile phase containing formic acid (pH 4.3), 5% acetone and 0.002% triethylamine using a separation voltage of 12 kV. The detection limits for four Sudan dyes ranged from 8.0 x 10(-7) to 1.2 x 10(-6) mol/L. To evaluate the feasibility and reliability of this method, the proposed pCEC-AD method was further demonstrated with hot chilli samples spiked with Sudan dyes.
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Affiliation(s)
- Shaofeng Liu
- The Key Laboratory of Analysis and Detection Technology for Food Safety (Fuzhou University), Ministry of Education, Department of Chemistry, Fuzhou University, Fuzhou, Fujian, China
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17
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Debowski JK. SELECTED APPLICATIONS OF CAPILLARY ELECTROCHROMATOGRAPHY IN THE PHARMACEUTICAL INDUSTRY: TO BUY OR NOT TO BUY? J LIQ CHROMATOGR R T 2007. [DOI: 10.1081/jlc-120013988] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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18
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Lü H, Wang J, Wang X, Lin X, Wu X, Xie Z. Rapid separation and determination of structurally related anthraquinones in Rhubarb by pressurized capillary electrochromatography. J Pharm Biomed Anal 2007; 43:352-7. [PMID: 16875795 DOI: 10.1016/j.jpba.2006.06.023] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Revised: 06/04/2006] [Accepted: 06/12/2006] [Indexed: 10/24/2022]
Abstract
A pressurized capillary electrochromatography (pCEC) with monolithic column has been developed for the rapid separation and determination of five structurally related anthraquinones in Rhubarb. The possibility of rapid separation resulted from the unique pore structure with high permeability and favorable mass transfer characteristics of the monolithic stationary phase. The effect factors such as organic modifier, acidity and concentration of running buffer, separation voltage were investigated to acquire the optimum condition. In the 220 nm wavelengths, the five anthraquinones could be baseline-separated rapidly within 5 min with the separation voltage of -20 kV in 10 mmol/L phosphate buffer (pH 6.2) containing 65% acetonitrile. The calibration graphs of rhein, aloe-emodin, emodin chrysophanol and physcion were linear by plotting the peak area against the analytes concentration over the range of 0.2-65, 0.1-30, 0.1-55, 0.5-30 and 0.5-55 microg/mL, respectively. The detection limits of five anthraquinones were ranged from 0.06 to 0.2 microg/mL and the recoveries of Rhubarb samples were about 81.3-86.4% (R.S.D.< or = 5.2%). This proposed method was successfully applied to determination of the five analytes in Rhubarb with satisfactory results.
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Affiliation(s)
- Haixia Lü
- The Key Laboratory of Analysis and Detection Technology for Food Safety (Fuzhou University), Ministry of Education, Fuzhou, Fujian 350002, China
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19
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Ye F, Xie Z, Wong KY. Monolithic silica columns with mixed mode of hydrophilic interaction and weak anion-exchange stationary phase for pressurized capillary electrochromatography. Electrophoresis 2006; 27:3373-80. [PMID: 16865668 DOI: 10.1002/elps.200500869] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A silica-based monolithic column as polar stationary phase is proposed for pressurized CEC (pCEC). The monolithic silica matrix from a sol-gel process was chemically modified by 3-aminopropyltrimethoxysilane to produce a column for hydrophilic interaction applications. The amino groups on the surface of the polar stationary phase generated anodic EOF under acidic conditions and served at the same time as a weak anion-exchanger. The anion solutes such as nucleotides were separated by the mixed mode mechanism, which comprised hydrophilic interaction, weak anion-exchange, and electrophoresis. The influences of buffer concentration and organic modifier content on the separation of nucleotides by pCEC have been investigated. In addition, the monolithic silica columns were also able to separate various polar compounds such as phenols, nucleic acid bases, and nucleosides in the hydrophilic interaction CEC mode.
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Affiliation(s)
- Fanggui Ye
- The MOE Key Laboratory of Analysis and Detection Technology for Food Safety, Department of Chemistry, Fuzhou University, Fuzhou, Fujian, China
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20
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Qu Q, Lu X, Huang X, Hu X, Zhang Y, Yan C. Preparation and evaluation of C18-bonded 1-µm silica particles for pressurized capillary electrochromatography. Electrophoresis 2006; 27:3981-7. [PMID: 16983634 DOI: 10.1002/elps.200600012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Nonporous silica spheres (1 microm) were synthesized and bonded with octadecylsilane functionality. These stationary phase particles were packed electrokinetically into fused-silica capillaries with 100 microm id for a length of 20 cm, which was evaluated by using pressurized CEC (pCEC). The efficiency of the C18 RP column was characterized through the theoretical plates of thiourea, benzyl alcohol, toluene, styrene, and naphthalene. The effects of experimental parameters such as the applied voltage, sample size, pump flow rate, pH value and the concentration of the buffer solution, and the content of methanol in the mobile phase, on-column efficiency were evaluated. Column efficiency as high as 200 000 theoretical plates per meter for naphthalene was obtained with the optimal condition of 70% v/v methanol and 30% v/v of 10 mmol/L phosphate buffer (pH 7.8) at an applied voltage of 10 kV and a supplementary pressure of 500 psi.
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Affiliation(s)
- Qishu Qu
- Jiangsu Key Laboratory of Environmental Materials and Environmental Engineering, College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, PR China.
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21
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Ye F, Xie Z, Wu X, Lin X, Chen G. Separation of Polar and Basic Compounds in Hydrophilic Interaction Pressurized CEC Using Diethylenetriaminopropyl Silica Monolithic Columns. Chromatographia 2006. [DOI: 10.1365/s10337-006-0022-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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22
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Lin Z, Xie Z, Lü H, Lin X, Wu X, Chen G. On-Column Coaxial Flow Chemiluminescence Detection for Underivatized Amino Acids by Pressurized Capillary Electrochromatography Using a Monolithic Column. Anal Chem 2006; 78:5322-8. [PMID: 16878866 DOI: 10.1021/ac060152y] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A new method for pressurized capillary electrochromatography (pCEC) coupling with chemiluminescence (CL) detection using a modified on-column coaxial flow detection interface was developed. To evaluate the feasibility and reliability of the experimental setup, the typical CL compounds luminol and isoluminol were separated and detected by using this pCEC-CL system. A detailed investigation of CL detection interface and postcolumn CL reagent flow rate parameters was described. The excellent resolution and detection sensitivity was achieved by using 3-microm ODS-C18 packed column with 30% ACN (v/v), 5 mmol/L phosphate buffer (pH 8.0). Moreover, with the presence of Co(II) (1.0 x 10(-4) mol/L) in the mobile phase, the linear range of the concentration for luminol was 2.0 x 10(-9)-2.0 x 10(-6) mol/L with a detection limit (S/N = 3) of 2.0 x 10(-10) mol/L, and 2.5 x 10(4) theoretical plates was achieved. In addition, separation and detection of the underivatized amino acids (l-threonine and l-tyrosine) were accomplished by using a polymerized monolithic column based on the principle of the luminol-H2O2-Cu(II)-amino acid CL system. Under the optimum conditions, the mixture of amino acids was efficiently separated with satisfactory results.
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Affiliation(s)
- Zian Lin
- Ministry of Education Key Laboratory of Analysis and Detection Technology for Food-Safety, and Department of Chemistry, Fuzhou University, Fuzhou, 350002, China
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23
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Ye F, Xie Z, Wu X, Lin X, Chen G. Phenylaminopropyl silica monolithic column for pressure assisted capillary electrochromatography. J Chromatogr A 2006; 1117:170-5. [PMID: 16620853 DOI: 10.1016/j.chroma.2006.03.085] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2006] [Revised: 03/19/2006] [Accepted: 03/24/2006] [Indexed: 11/25/2022]
Abstract
A novel stationary phase phenylaminopropyl silica (PhA-silica) monolith was successfully prepared for pressure assisted capillary electrochromatography (pCEC). The monolithic silica matrix from a sol-gel process was chemically modified by using [3-(phenylamino)propyl]trimethoxysilane as surface modification reagent to produce the phenylaminoporpyl function. The secondary amino groups on the surface of the monolithic stationary phase contributed to the generation of anodic electroosmotic flow (EOF) under acidic conditions. The phenyl group together with the spacer (-(CH(2))(3)-) in PhA-silica provides sufficient hydrophobic properties. To evaluate the column performance, effects of buffer pH and mobile phase composition on the mobile phase linear velocity and the retention factors of alkylbenzenes, phenols and anilines were investigated in pCEC mode. The monolithic stationary phases exhibit typical reversed-phase (RP) electrochromatographic behavior toward neutral solutes. Hydrophobic as well as electrophoretic migration process within the monoliths was observed for the separation of basic solutes such as anilines without peak tailing.
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Affiliation(s)
- Fanggui Ye
- The Ministry of Education Key Laboratory of Analysis and Detection Technology for Food Safety, and Department of Chemistry, Fuzhou University, Fuzhou, Fujian 350002, China
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24
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Espinosa Bosch M, Ruiz Sánchez AJ, Sánchez Rojas F, Bosch Ojeda C. Determination of paracetamol: historical evolution. J Pharm Biomed Anal 2006; 42:291-321. [PMID: 16716555 DOI: 10.1016/j.jpba.2006.04.007] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2006] [Revised: 04/03/2006] [Accepted: 04/10/2006] [Indexed: 10/24/2022]
Abstract
Paracetamol is a common analgesic and antipyretic drug that is used for the relief of fever, headaches and other minor aches and pains. Their determination in pharmaceuticals is of paramount importance, since an overdose of paracetamol can cause fulminating hepatic necrosis and other toxic effects. Many analytical methodologies have been proposed for the determination of paracetamol. The aim of the present study is to evaluate the utility of different techniques for quantification of paracetamol content in pharmaceutical formulations and biological samples.
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Affiliation(s)
- M Espinosa Bosch
- Department of Analytical Chemistry, Faculty of Sciences, University of Málaga, Campus Teatinos, 29071 Málaga, Spain
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25
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Liu S, Xie Z, Wu X, Lin X, Guo L, Chen G. Separation of structurally related estrogens using isocratic elution pressurized capillary electrochromatography. J Chromatogr A 2005; 1092:258-62. [PMID: 16199236 DOI: 10.1016/j.chroma.2005.08.024] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2005] [Revised: 08/04/2005] [Accepted: 08/08/2005] [Indexed: 11/29/2022]
Abstract
In this paper, the pressurized capillary electrochromatography (pCEC) with UV detection was utilized for the separation and determination of three structurally related estrogens, such as diethylstilbestrol (DES), hexestrol (HEX) and dienestrol (DE), which were difficult to be separated by capillary electrophoresis (CE) and HPLC due to their similarity in the structure and charge-to-mass ratios. Experiments were carried out in a commercially available pCEC instrument using a capillary column packed with 3 microm octadecyl silica (ODS). Surfactant sodium dodecyl sulfate (SDS) was introduced in the mobile phase to enhance the speed of analysis. The effective factors on the retention time and separation resolution, such as the applied voltage, supplementary pressure, the pH and the concentration of the buffer solution, the concentration of SDS, and the content of acetonitrile in the mobile phase, were evaluated. Based on the investigation, 31% (v/v) acetonitrile and 69% (v/v) of 10 mmol/L phosphate buffer (pH 6.5) containing 1.0 mmol/L SDS at an applied voltage of -12 kV and a supplementary pressure of 1000 psi were found to be the optimal conditions for pCEC to separate the three estrogens. The method also had been applied to the analysis of fish muscle samples spiked with estrogens.
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Affiliation(s)
- Shaofeng Liu
- Institute of Food Safety and Environmental Monitoring, Fuzhou University, Fuzhou 350002, China
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26
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Webb AG. Nuclear magnetic resonance coupled microseparations. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2005; 43:688-96. [PMID: 16049953 DOI: 10.1002/mrc.1616] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The increased separation efficiency afforded by reducing the size of the separation column has resulted in 'microseparations' becoming an important component in many chemical and biochemical applications. The coupling of microseparations with NMR detection is an area of increasing interest owing to the high structural information of NMR. In order to couple efficiently with the separation, the NMR detector must be reduced in size to correspond to that of the separation peak. This paper summarizes some of the approaches used in coupling NMR detection with pressure-driven and electrophoretic microseparations, the design of small NMR detectors and applications of this technology.
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Affiliation(s)
- A G Webb
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 61801, USA.
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27
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Webb AG. Microcoil nuclear magnetic resonance spectroscopy. J Pharm Biomed Anal 2005; 38:892-903. [PMID: 16087050 DOI: 10.1016/j.jpba.2005.01.048] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Revised: 01/15/2005] [Accepted: 01/22/2005] [Indexed: 11/16/2022]
Abstract
In comparison with most analytical chemistry techniques, nuclear magnetic resonance has an intrinsically low sensitivity, and many potential applications are therefore precluded by the limited available quantity of certain types of sample. In recent years, there has been a trend, both commercial and academic, towards miniaturization of the receiver coil in order to increase the mass sensitivity of NMR measurements. These small coils have also proved very useful in coupling NMR detection with commonly used microseparation techniques. A further development enabled by small detectors is parallel data acquisition from many samples simultaneously, made possible by incorporating multiple receiver coils into a single NMR probehead. This review article summarizes recent developments and applications of "microcoil" NMR spectroscopy.
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Affiliation(s)
- A G Webb
- Department of Electrical and Computer Engineering, and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 4221 Beckman Institute, 405 N. Mathews, Urbana, IL 61801, USA.
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28
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Liu S, Wu X, Xie Z, Lin X, Guo L, Yan C, Chen G. On-line coupling of pressurized capillary electrochromatography with end-column amperometric detection for analysis of estrogens. Electrophoresis 2005; 26:2342-50. [PMID: 15920782 DOI: 10.1002/elps.200500082] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
An improved technique, pressurized capillary electrochromatography (pCEC) coupling with end-column amperometric detection (AD), was developed and used for the separation and determination of estrogens. The effects of pH value, composition of mobile phase, concentration of the surfactant sodium dodecyl sulfate (SDS) and applied voltage on separation were investigated. The electrochemical oxidation of diethylstilbestrol (DES), dienestrol (DE), and hexestrol (HEX) could be reliably monitored with a carbon electrode at 0.9 V (vs. Ag/AgCl). The pCEC analyses were performed on a capillary separation column packed with 3 microm C18 particles with an acetonitrile/water (31%: 69%) mobile phase containing Tris buffer (5 mmol/L, pH 4.5) and 4 mmol/L SDS. High voltage up to 12 kV reduced the retention time dramatically and still provided a baseline resolution. In addition, supplementary pressure prevented bubble formation and provided reliability and reproducibility of the pCEC performance. The detection limits for the three estrogens ranged from 1.2 to 2.2x10(-7) mol/L, about 10 20-fold lower than those obtained with pCEC-UV detection. To evaluate the feasibility and reliability of this system, the proposed pCEC-AD method was further demonstrated with fish muscle samples spiked with estrogens.
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Affiliation(s)
- Shaofeng Liu
- Institute of Food Safety and Environmental Monitoring, Fuzhou University, Fuzhou, China
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29
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Zhang X, Webb AG. Magnetic resonance microimaging and numerical simulations of velocity fields inside enlarged flow cells used for coupled NMR microseparations. Anal Chem 2005; 77:1338-44. [PMID: 15732916 PMCID: PMC2754838 DOI: 10.1021/ac048532b] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The coupling of various chemical microseparation methods with small-scale NMR detection is a growing area in analytical chemistry. The formation of enlarged flow cells within the active volume of the NMR detector can significantly increase the coil filling factor and hence the signal-to-noise ratio of the NMR spectra. However, flow cells can also lead to deterioration of the separation efficiency due to the development of complex flow patterns, the form of which depend on the particular geometry of the flow cell and the flow rate used. In this study, we investigated the flow characteristics in different flow cell geometries relevant to the coupling of capillary liquid chromatography and NMR. Computational fluid dynamics was used to simulate fluid flow inside flow cells with a volume of approximately 1 microL. Magnetic resonance microimaging was used to measure experimentally the velocity fields inside these flow cells. The results showed good agreement between experiment and simulation and demonstrated that a relatively gradual expansion and contraction is necessary to avoid areas of weak recirculation and strong radial velocities, both of which can potentially compromise separation efficiency.
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Affiliation(s)
- Xiaofeng Zhang
- Department of Electrical and Computer Engineering; and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana—Champaign, Urbana, Illinois 61801
| | - Andrew G. Webb
- Department of Electrical and Computer Engineering; and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana—Champaign, Urbana, Illinois 61801
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30
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Wolters AM, Jayawickrama DA, Sweedler JV. Comparative analysis of a neurotoxin from Calliostoma canaliculatum by on-line capillary isotachophoresis/1H NMR and diffusion 1H NMR. JOURNAL OF NATURAL PRODUCTS 2005; 68:162-167. [PMID: 15730236 DOI: 10.1021/np030302p] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
NMR spectroscopy has been coupled on-line to capillary isotachophoresis (cITP) to enhance structural analyses of dilute charged species through separation and sample concentration. Microcoils, the most mass-sensitive NMR probes available, provide optimal detection for cITP/NMR. To evaluate the utility of cITP/NMR for natural product analysis, a homogenate of the hypobranchial gland from the marine snail Calliostoma canaliculatum containing a cationic neurotoxin (1, a disulfide-bonded dimer of 6-bromo-2-mercaptotryptamine) was studied. For comparison, hypobranchial gland homogenate was also examined by diffusion-NMR, an alternative approach for NMR mixture analysis. cITP/NMR concentrated the neurotoxin by almost 20-fold and isolated it from some of the other components present in the matrix. However, a minor component, likely a precursor or degradant, co-migrated with compound 1. Diffusion-NMR also did not resolve the two, indicating that the compounds possessed similar diffusion coefficients and electrophoretic mobilities. The strengths and limitations of the two approaches for NMR mixture analysis are discussed.
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Affiliation(s)
- Andrew M Wolters
- Department of Chemistry and the Beckman Institute, University of Illinois, Urbana, IL 61801, USA
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31
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Jayawickrama DA, Sweedler JV. Dual Microcoil NMR Probe Coupled to Cyclic CE for Continuous Separation and Analyte Isolation. Anal Chem 2004; 76:4894-900. [PMID: 15307803 DOI: 10.1021/ac049390o] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Capillary electrophoresis (CE)-nuclear magnetic resonance (NMR) spectroscopy combines the separation efficiency of CE and the information-rich detection capabilities of NMR. However, the temporally narrow CE peaks reduce NMR sensitivity and prevent on-line multidimensional NMR acquisitions. In this work, cyclic CE with multicoil NMR instrumentation is developed to perform CE in multiple closed loops. As a proof of concept, a two-loop five-junction capillary configuration creates two connected yet independently operable fluidic loops. With appropriate voltage switching, analytes can be directed as desired around or between the loops, and a particular analyte band can be parked in one NMR detector coil while CE continues in the second loop and monitored with a second NMR detector coil. The separation of a mixture of amino acids (Ala, Val, Thr) is achieved in two cycles. After one CE cycle, Ala is separated and COSY data are recorded in one loop while Val and Thr are separated in the second loop. At the end of the second cycle, both Val and Thr are separated and multidimensional NMR spectra acquired. With this instrumentation and appropriate protocols, two-dimensional NMR data acquisition and CE separation are achieved simultaneously.
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Affiliation(s)
- Dimuthu A Jayawickrama
- Department of Chemistry and the Beckman Institute, University of Illinois, Urbana, Illinois 61801, USA
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32
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Jiskra J, Claessens HA, Cramers CA. Stationary and mobile phases in capillary electrochromatography (CEC). J Sep Sci 2003. [DOI: 10.1002/jssc.200301305] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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33
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Eriksson BO, Andersson MBO, Blomberg LG. Deviation from Ohm’s law in electric field assisted capillary liquid chromatography. J Chromatogr A 2003; 1010:17-24. [PMID: 14503812 DOI: 10.1016/s0021-9673(03)01018-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Earlier studies of electric field assisted LC (EF-LC) have shown that the effect on charged analytes of the application of an electric field over a capillary LC column is relatively small. Charged analytes can only be affected by the electric field while present in the mobile phase, which makes the effective time for influence of the electric field t(0) independent of retention time. Because the charged analytes only can be affected for a short time the electric field strength ought to be high in order to increase the impact of the electric field on the separation. We have, however, found that only a relatively low electric field strength can be used in EF-LC when pressure is used as main driving force. The useful field strength was limited by a dramatic increase in the current. This increase in current was found to origin from an increased concentration of buffer ions that have an electrophoretic mobility towards the pumped flow.
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Affiliation(s)
- Björn O Eriksson
- Department of Chemistry, Karlstad University, SE-651 88 Karlstad, Sweden
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34
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Jayawickrama DA, Sweedler JV. Hyphenation of capillary separations with nuclear magnetic resonance spectroscopy. J Chromatogr A 2003; 1000:819-40. [PMID: 12877202 DOI: 10.1016/s0021-9673(03)00447-3] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The hyphenation of small-volume separations to information-rich detection offers the promise of unmatched analytical information on the components of complex mixtures. Nuclear magnetic resonance (NMR) spectroscopy provides information about molecular structure, although sensitivity remains an issue for on-line NMR detection. This is especially true when hyphenating NMR to capillary separations as the observation time and analyte mass are decreased to the point where reduced information is obtained from the eluting analytes. Because of these limitations, advances in instrumental performance have a large impact on the overall performance of a separation-NMR system. Instrumental aspects and the capabilities of cLC-NMR, CEC-NMR and CE-NMR are reviewed, and applications that have used this technology highlighted. Recent trends towards small volume capillary scale separations are emphasized, as is the recent success of capillary-isotachophoresis (cITP)-NMR.
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Affiliation(s)
- Dimuthu A Jayawickrama
- Department of Chemistry, Beckman Institute, University of Illinois, Urbana, IL 61801, USA
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35
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Maiwald M, Fischer HH, Kim YK, Hasse H. Quantitative on-line high-resolution NMR spectroscopy in process engineering applications. Anal Bioanal Chem 2003; 375:1111-5. [PMID: 12733025 DOI: 10.1007/s00216-002-1723-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2002] [Revised: 11/21/2002] [Accepted: 11/21/2002] [Indexed: 10/20/2022]
Abstract
In many technical processes, complex multicomponent mixtures have to be handled, for example, in reaction or separation equipment. High-resolution NMR spectroscopy is an excellent tool to study these mixtures and gain insight in their behavior in the processes. For on-line studies under process conditions, flow NMR probes can be used in a wide range of temperature and pressure. A major challenge in engineering applications of NMR spectroscopy is the need for quantitative evaluation. Flow rates, recovery times, and other parameters of the on-line NMR experiments have to be optimized for this purpose. Since it is generally prohibitive to use deuterated solvents in engineering applications, suitable techniques for field homogenization and solvent signal suppression are needed. Two examples for the application of on-line NMR spectroscopic experiments in process engineering are presented, studies on chemical equilibria and reaction kinetics of the technically important system formaldehyde-water-methanol and investigations on reactive gas absorption of CO(2) in aqueous solutions of monoethanolamine.
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Affiliation(s)
- Michael Maiwald
- Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, Pfaffenwaldring 9, 70550, Stuttgart, Germany
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36
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Biomedical applications of directly-coupled chromatography–nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s1567-7192(03)80011-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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37
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38
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Abstract
NMR spectroscopy is increasingly being used to characterize microliter and smaller-volume samples. Substances at picomole levels have been identified using NMR spectrometers equipped with microcoil-based probes. NMR probes that incorporate multiple sample chambers enable higher-throughput NMR experiments. Hyphenation of capillary-scale separations and microcoil NMR has also decreased analysis time of mixtures. For example, capillary isotachophoresis/NMR allows the highest mass sensitivity nanoliter-volume flow cells to be used with low microliter volume samples because isotachophoresis concentrates the microliter volume sample into the nanoliter volume NMR detection probe. In addition, the diagnostic capabilities of NMR spectroscopy allow the physico-chemical aspects of a capillary separation process to be characterized on-line. Because of such advances, the application of NMR to smaller samples continues to grow.
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Affiliation(s)
- Andrew M Wolters
- Department of Chemistry and the Beckman Institute, University of Illinois, Urbana 61801, USA
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39
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Wolters AM, Jayawickrama DA, Larive CK, Sweedler JV. Capillary isotachophoresis/NMR: extension to trace impurity analysis and improved instrumental coupling. Anal Chem 2002; 74:2306-13. [PMID: 12038755 DOI: 10.1021/ac015744p] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Building upon its promising initial performance, the online coupling of capillary isotachophoresis (cITP) to nuclear magnetic resonance (NMR) is extended to trace impurity analysis. By simultaneously concentrating and separating dilute charged species on the basis of their electrophoretic mobility, cITP greatly facilitates NMR structural elucidation. cITP/NMR appears particularly attractive for identifying trace charged synthetic and natural organic compounds obscured by large excesses of other components. A 9.4 microL injection of 200 microM (1.9 nmol) atenolol in a 1000-fold excess of sucrose (200 mM) is analyzed by cITP/NMR. A microcoil, the most mass sensitive NMR probe, serves as the detector as it provides optimal NMR observation of the capillary-scale separation. cITP successfully isolates the atenolol from the sucrose while concentrating it 200-fold to 40 mM before presentation to the 30 nL observe volume microcoil, thereby enabling rapid 1H NMR spectral acquisition of atenolol (experimental time of 10 s) without obstruction from sucrose. For this particular probe and sample, the stacking efficiency is near the theoretical limit as 67% of the sample occupies the 1 mm long microcoil during peak maximum. A multiple-coil probe with two serial 1 mm long microcoils arranged 1 cm apart has been developed to facilitate peak trapping and sample band positioning during cITP/NMR.
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Affiliation(s)
- Andrew M Wolters
- Department of Chemistry, University of Illinois, Urbana 61801, USA
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40
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Fernández FM, Vadillo JM, Kimmel JR, Wetterhall M, Markides K, Rodriguez N, Zare RN. Hadamard transform time-of-flight mass spectrometry: a high-speed detector for capillary-format separations. Anal Chem 2002; 74:1611-7. [PMID: 12033252 DOI: 10.1021/ac015673u] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This work demonstrates that with an intrinsic duty cycle of 50% and spectral storage speeds up to 277 spectra s(-1) Hadamard transform time-of-flight mass spectrometry (HT-TOFMS) is a promising detector for any capillary-format separation that can be coupled to MS by electrospray ionization. Complete resolution of the components of a nine-peptide standard was achieved by coupling pressurized-capillary electrophoresis (pCE) to HT-TOFMS. The addition of pressure to the separation capillary decreased analysis times and stabilized the electrospray ionization source. Pulsed-pressurized injection of reserpine was used to experimentally simulate narrower peaks than those obtained in the pCE. HT-TOFMS was able to sample peaks having widths in the millisecond range.
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