1
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Cai Y, Niu JC, Liu YQ, Du XL, Wu ZY. Online sample clean-up and enrichment of proteins from salty media with dynamic double gradients on a paper fluidic channel. Anal Chim Acta 2020; 1100:149-155. [DOI: 10.1016/j.aca.2019.11.048] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 11/20/2019] [Indexed: 10/25/2022]
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2
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Dziomba S, Bekasiewicz A, Prahl A, Bączek T, Kowalski P. Improvement of derivatized amino acid detection sensitivity in micellar electrokinetic capillary chromatography by means of acid-induced pH-mediated stacking technique. Anal Bioanal Chem 2014; 406:6713-21. [PMID: 25146356 PMCID: PMC4182592 DOI: 10.1007/s00216-014-8104-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 08/08/2014] [Accepted: 08/11/2014] [Indexed: 12/05/2022]
Abstract
Derivatization is a frequently used sample preparation procedure applicable to the enhancement of analyte detection sensitivity. Amino acids mostly require derivatization prior to electrophoretic or chromatographic analysis, especially if spectrophotometric detection is used. This study presents an on-line preconcentration technique for derivatized amino acids. The sensitivity of the method was improved by the utilization of the proposed acid-induced pH-mediated stacking mechanism. The method is demonstrated by preconcentration of amino acids labeled with 2,4-dinitrofluorobenzene. Use of optimized conditions for a large sample volume injection (40 s, 13.8 kPa) followed by electrokinetic injection of 0.1 M HCl (20 s, 10 kV) gave a 20- to 30-fold enhancement of sensitivity. The significance of the sweeping mechanism and pseudo-isotachophoresis for the on-line sample focusing and the influence of parameters on the preconcentration process were discussed. The applicability of the elaborated method was demonstrated using human urine samples.
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Affiliation(s)
- Szymon Dziomba
- Department of Pharmaceutical Chemistry, Medical University of Gdańsk, 107 Hallera Street, 80-416, Gdańsk, Poland
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3
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Lu Y, Bai H, Kong C, Zhong H, Breadmore MC. Analysis of brazilin and protosappanin B in sappan lignum by capillary zone electrophoresis with acid barrage stacking. Electrophoresis 2014; 34:3326-32. [PMID: 24150968 DOI: 10.1002/elps.201300402] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 09/16/2013] [Accepted: 09/23/2013] [Indexed: 11/05/2022]
Abstract
A method was developed to determine brazilin and protosappanin B in natural products by CE after acid barrage stacking. The optimum conditions were as follows: a BGE of 20 mM sodium tetraborate (pH 9.2) containing 6% v/v of methanol, hydrodynamic injection (0.5 psi, 65 s) followed by hydrodynamic injection of 150 mM citric acid (pH 2.3; 0.5 psi, 22 s), and separated with +25 kV. Under these conditions, brazilin and protosappanin B were separated with a sample-to-sample time less than 13 min and detection limits of 0.28 μg/mL and 0.15 μg/mL, respectively. The applicability of the developed method was demonstrated by the detection of brazilin and protosappanin in methanol extract of sappan lignum.
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Affiliation(s)
- Yuanqi Lu
- Analysis and Testing Centre, Dezhou University, Dezhou, P. R. China; Institute of Materia Medica, Shandong Academy of Medical Sciences, Jinan, P. R. China; Key Laboratory of Coordination Chemistry and Functional Materials in Universities of Shandong, Dezhou University, Dezhou, P. R. China
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4
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Incorporation of polyamidoamine sweeping and electrokinetic supercharging for in-line DNA fragment preconcentration. J Chromatogr A 2013; 1280:112-6. [DOI: 10.1016/j.chroma.2013.01.043] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Revised: 12/28/2012] [Accepted: 01/08/2013] [Indexed: 11/23/2022]
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5
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Shin A, Lee M, Kim S, Kang SH. On-line capillary electrophoresis for enhanced detection sensitivity of feline panleukopenia virus. J Chromatogr B Analyt Technol Biomed Life Sci 2012; 909:22-5. [PMID: 23153639 DOI: 10.1016/j.jchromb.2012.10.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 09/30/2012] [Accepted: 10/03/2012] [Indexed: 10/27/2022]
Abstract
A rapid on-line capillary electrophoresis (CE) method for highly sensitive detection of DNA molecules with specific lengths was developed based on the combination of base stacking (BS) and programmed field strength gradients (PFSG). The BS method has been performed for on-column concentration to improve detection sensitivity without any modification of the CE system. PFSG increased the electrophoretic velocity of DNA molecules, which effectively decreased analysis time. Using the BS and PFSG combination, the amplified PCR product (340-bp DNA) of cats infected with feline panleukopenia virus was detected within 6.5min. Detection sensitivity (∼10-fold) was enhanced compared to conventional CE analysis. The combined on-line CE/BS-PFSG methodology could be an effectively rapid analysis technique for the highly sensitive detection of disease-related specific DNA molecules.
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Affiliation(s)
- Ahram Shin
- Department of Applied Chemistry, College of Applied Science, Kyung Hee University, Yongin-si, Gyunggi-do 446-701, Republic of Korea
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6
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Duan J, Hu B, He M. Nanometer-sized alumina packed microcolumn solid-phase extraction combined with field-amplified sample stacking-capillary electrophoresis for the speciation analysis of inorganic selenium in environmental water samples. Electrophoresis 2012; 33:2953-60. [DOI: 10.1002/elps.201200156] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Revised: 06/12/2012] [Accepted: 07/11/2012] [Indexed: 11/10/2022]
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7
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Shin AR, Kang SH. DNA Concentration Effect of Various Hydroxide Compounds on Stacking in Capillary Electrophoresis. B KOREAN CHEM SOC 2011. [DOI: 10.5012/bkcs.2011.32.12.4316] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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8
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Sweeping under controlled electroosmotic flow and micellar electrokinetic chromatography for on-line concentration and determination of trace phlorizin and quercitrin in urine samples. J Pharm Biomed Anal 2011; 56:330-5. [DOI: 10.1016/j.jpba.2011.05.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2011] [Revised: 04/25/2011] [Accepted: 05/15/2011] [Indexed: 11/17/2022]
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9
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Feng A, Tran NT, Chen C, Hu J, Taverna M, Zhou P. In-line coupling SPE and CE for DNA preconcentration and separation. Electrophoresis 2011; 32:1623-30. [PMID: 21626518 DOI: 10.1002/elps.201000484] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Revised: 01/10/2011] [Accepted: 01/11/2011] [Indexed: 11/08/2022]
Abstract
An in-line SPE method coupled to CE was developed for the analysis of DNA. The amino silica monolith was prepared in situ by polymerization of tetraethoxysilane and N-(β-aminoethyl)-γ-aminopropyltriethoxysilane in ethanol aqueous solution at the inlet end of a 100 μm id fused-silica capillary, and the remaining part of the capillary was used as separation channel. The procedure for this in-line SPE-CE method was constructed on the basis of investigation on operational conditions such as the introduction mode of sieving matrix, the composition of elution solvent and the elution time. Twenty millimolar ammonium hydroxide was demonstrated to be effective for DNA desorption from the monolith, and linear poly(N-isopropylacrylamide) was used as the separation matrix. The proposed method could achieve limits of detection of 0.065-0.123 ng/mL for six DNA fragments ranging 100-2000 bp. Compared with conventional CE, preconcentration factors of over 100 times were obtained. The applicability of the in-line SPE-CE method was further demonstrated by analyzing plasmid DNA from Escherichia coli crude lysate.
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Affiliation(s)
- Airong Feng
- Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, P. R. China
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10
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Oita I, Halewyck H, Pieters S, Dejaegher B, Thys B, Rombaut B, Vander Heyden Y. Rational use of stacking principles for signal enhancement in capillary electrophoretic separations of poliovirus samples. J Pharm Biomed Anal 2011; 55:135-45. [DOI: 10.1016/j.jpba.2010.12.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Accepted: 12/16/2010] [Indexed: 11/29/2022]
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11
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Rapid and accurate determination of deoxyribonucleoside monophosphates from DNA using micellar electrokinetic chromatography with a cationic surfactant additive. Anal Bioanal Chem 2011; 400:2131-40. [DOI: 10.1007/s00216-011-4915-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Revised: 03/14/2011] [Accepted: 03/14/2011] [Indexed: 11/26/2022]
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12
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Zhang S, Jiang C, Jia L. Tetrabutylammonium phosphate-assisted separation of multiplex polymerase chain reaction products in non-gel sieving capillary electrophoresis. Anal Biochem 2011; 408:284-8. [DOI: 10.1016/j.ab.2010.09.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Revised: 09/13/2010] [Accepted: 09/15/2010] [Indexed: 10/19/2022]
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13
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Ye H, Xia S, Lin W, Yu L, Xu X, Zheng C, Liu X, Chen G. CE-ESI-MS coupled with dynamic pH junction online concentration for analysis of peptides in human urine samples. Electrophoresis 2010; 31:3400-6. [DOI: 10.1002/elps.201000194] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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14
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Thaitrong N, Toriello NM, Del Bueno N, Mathies RA. Polymerase chain reaction-capillary electrophoresis genetic analysis microdevice with in-line affinity capture sample injection. Anal Chem 2009; 81:1371-7. [PMID: 19140739 DOI: 10.1021/ac802057f] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An integrated polymerase chain reaction (PCR)-capillary electrophoresis (CE) microdevice with an efficient in-line affinity-based injector has been developed for genetic analysis. Double stranded DNA PCR amplicons generated in an integrated 250 nL PCR reactor are captured, purified, and preconcentrated by an oligonucleotide probe immobilized in an in situ polymerized gel matrix followed by thermal release and injection into the CE-separation channel. This in-column injector employs a photopolymerized oligonucleotide-modified acrylamide capture gel to eliminate band broadening and increase the injection efficiency to 100%. The on-chip generated PCR amplicons processed on this microdevice exhibit a 3-5 fold increase in signal intensities and improved resolution compared to our previous T-shaped injector. Multiplex analysis of 191-bp amplicons from Escherichia coli O157 and 256-bp amplicons from E. coli K12 is achieved with a 6-fold increase in resolution. These advances are exploited to successfully detect E. coli O157 in a 500-fold higher background of E. coli K12. This microdevice with in-line affinity capture gel injection provides an improved platform for low-volume, high sensitivity, fully integrated genetic analysis.
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Affiliation(s)
- Numrin Thaitrong
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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15
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Xie HY, He YZ, Gan WE, Fu GN, Li L, Han F, Gao Y. On-column liquid–liquid–liquid microextraction coupled with base stacking as a dual preconcentration method for capillary zone electrophoresis. J Chromatogr A 2009; 1216:3353-9. [DOI: 10.1016/j.chroma.2009.01.070] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2008] [Revised: 01/17/2009] [Accepted: 01/23/2009] [Indexed: 10/21/2022]
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16
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Wang L, Liu D, Chen H, Zhou X. A simple and sensitive transient ITP method for on-chip analysis of PCR samples. Electrophoresis 2008; 29:4976-83. [DOI: 10.1002/elps.200800258] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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17
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Low-temperature bath/high-conductivity zone/stacking micellar electrokinetic chromatography for the analysis of phenolic acids in coffee drink. J Chromatogr A 2008; 1212:137-44. [DOI: 10.1016/j.chroma.2008.10.027] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2008] [Revised: 10/06/2008] [Accepted: 10/07/2008] [Indexed: 11/23/2022]
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18
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Sueyoshi K, Kitagawa F, Otsuka K. Recent progress of online sample preconcentration techniques in microchip electrophoresis. J Sep Sci 2008; 31:2650-66. [PMID: 18693308 DOI: 10.1002/jssc.200800272] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Microchip electrophoresis (MCE) has been advanced remarkably by the applications of several separation modes and the integration with several chemical operations on a single planer substrate. MCE shows superior analytical performance, e.g., high-speed analysis, high resolution, low consumption of reagents, and so on, whereas low-concentration sensitivity is still one of the major problems. To overcome this drawback, various online sample preconcentration techniques have been developed in MCE over the past 15 years, which have successfully enhanced the detection sensitivity in MCE. This review highlights recent developments in online sample preconcentration in MCE categorized on the basis of "dynamic" and "static" methods. The dynamic techniques including field amplified stacking, ITP, sweeping, and focusing have been easily applied to MCE, which provide effective enrichments of various analytes. The static techniques such as SPE and filtration have also been combined with MCE. In the static techniques, extremely high preconcentration efficiency can be obtained, compared to the dynamic methods. This review provides comprehensive tables listing the applications and sensitivity enhancement factors of these preconcentration techniques employed in MCE.
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Affiliation(s)
- Kenji Sueyoshi
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan.
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19
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Zhang ZX, Zhang XW, Wang JJ, Zhang SS. Sequential preconcentration by coupling of field amplified sample injection with pseudo isotachophoresis-acid stacking for analysis of alkaloids in capillary electrophoresis. Anal Bioanal Chem 2008; 390:1645-52. [PMID: 18228006 DOI: 10.1007/s00216-008-1843-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Revised: 12/29/2007] [Accepted: 01/08/2008] [Indexed: 10/22/2022]
Abstract
A novel on-column sequential preconcentration method based on the combination of field-amplified sample injection induced by acetonitrile and pseudo isotachophoresis (ITP)-acid stacking is developed for simply but efficiently concentrating alkaloid cations in a high-salt sample matrix in capillary electrophoresis. Acetonitrile (70%) added to a sample solution with a high-salt sample matrix not only induces field-amplified sample stacking by decreasing conductivity but also acts as a termination reagent in the succeeding pseudo ITP. After sample injection had been completed, a plug of H(+) was injected electrokinetically and a neutralization reaction between H(+) and tartrate from the buffer solution produced a low conductivity zone, in which the injected analyte cations were further concentrated. With the sequential preconcentration method, a 3 orders of magnitude detection sensitivity (1,400-fold) increase could be observed compared with the conventional electrokinetic injection method, without compromising separation efficiency and peak shape, and detection limits of 0.1 ng/mL for myosmine and 0.3 ng/mL for anabasine with the conditions selected were achieved. The calibration curves demonstrated good linearity in the concentration ranges 1.3-600 ng/mL for myosmine and 4.9-900 ng/mL for anabasine, respectively. The proposed method has been used to analyze successfully trace alkaloids in cigarette samples.
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Affiliation(s)
- Zhao-Xiang Zhang
- Key Laboratory of Eco-chemical Engineering, Ministry of Education, College of Chemistry and Molecular Engineering, Qingdao University of Science Technology, Qingdao, 266042, China
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20
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Wei H, Qi C, Xu X, Zhang Z, Zhou Y, Cui Z, Zhang XE, Zhang C. Glycerol-salt Mediated Stacking of Nucleic Acids in CZE. Chromatographia 2008. [DOI: 10.1365/s10337-008-0523-8] [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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21
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Affiliation(s)
- Karel Klepárník
- Institute of Analytical Chemistry, Academy of Sciences of the Czech Republic, Veveří 97, CZ-602 00 Brno, Czech Republic
| | - Petr Boček
- Institute of Analytical Chemistry, Academy of Sciences of the Czech Republic, Veveří 97, CZ-602 00 Brno, Czech Republic
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22
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Deñola NL, Quiming NS, Saito Y, Jinno K. Simultaneous enantioseparation and sensitivity enhancement of basic drugs using large-volume sample stacking. Electrophoresis 2007; 28:3542-52. [PMID: 17806128 DOI: 10.1002/elps.200700299] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Simultaneous enantioseparation with sensitive detection of four basic drugs, namely methoxamine, metaproterenol, terbutaline and carvedilol, using a 20-mum ID capillary with native beta-CD as the chiral selector was demonstrated by the large-volume sample stacking method. The procedure included conventional sample loading either hydrodynamically or electrokinetically at longer injection times without polarity switching and EOF manipulation. In comparison to conventional injections, depending on the analyte, about several hundred- and a thousand-fold sensitivity enhancement was achieved with the hydrodynamic and the electrokinetic injections, respectively. The simple method developed was applied to the analysis of racemic analytes in serum samples and better recovery was achieved using hydrodynamic injection than electrokinetic injection.
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Affiliation(s)
- Nerissa L Deñola
- School of Materials Science, Toyohashi University of Technology, Toyohashi 441-8580, Japan
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23
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Chen H, Wu YH, Song DY, Zhang W, Dong XY, Li PW, Lu CM. On-line pre-concentration and UV determination of DNA fragments by dynamic coating capillary electrophoresis and its application to detection of genetically modified oilseed rape based on PCR. Microchem J 2007. [DOI: 10.1016/j.microc.2006.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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24
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Blazej RG, Kumaresan P, Cronier SA, Mathies RA. Inline injection microdevice for attomole-scale sanger DNA sequencing. Anal Chem 2007; 79:4499-506. [PMID: 17497827 DOI: 10.1021/ac070126f] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new affinity-capture-based inline purification, concentration, and injection method is developed for microchip capillary electrophoresis (CE) and used to perform efficient attomole-scale Sanger DNA sequencing separations. The microdevice comprises three axial domains for nanoliter-scale sequencing sample containment, sample plug formation, and high-resolution capillary gel electrophoresis. Purified and concentrated inline sample plugs are formed by electrophoretically driving Sanger sequencing extension fragments into an affinity-capture polymer network positioned within a CE separation channel. Extension fragments selectively hybridize and concentrate at the polymer interface while residual primer, nucleotides, and salts electrophorese out of the system. The plug is thermally released and injected into the CE channel by direct application of the separation voltage. To evaluate this system, 30 nL of sequencing sample prepared from 100 amol (60 million molecules) of human mitochondrial hypervariable region II amplicon was introduced into the microchip, purified, concentrated, and injected, generating a read length of 365 bases with 99% accuracy. This efficient inline injection system obviates the need for the excess sample that is required by cross-injection techniques, thereby enabling Sanger sequencing and other high-performance genetic analysis using DNA quantities approaching theoretical detection limits.
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Affiliation(s)
- Robert G Blazej
- UCSF/UC Berkeley Joint Bioengineering Graduate Group, University of California, Berkeley, California 94720, USA
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25
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Imami K, Monton MRN, Ishihama Y, Terabe S. Simple on-line sample preconcentration technique for peptides based on dynamic pH junction in capillary electrophoresis–mass spectrometry. J Chromatogr A 2007; 1148:250-5. [PMID: 17382949 DOI: 10.1016/j.chroma.2007.03.014] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2006] [Revised: 02/07/2007] [Accepted: 03/05/2007] [Indexed: 11/29/2022]
Abstract
We report an on-line sample preconcentration technique based on dynamic pH junction in capillary electrophoresis-mass spectrometry (CE-MS). For peptide analysis, the samples were dissolved in a solution with higher pH than the background solution (BGS), and were injected into the capillary as a long plug. The pH difference between the sample matrix and BGS caused changes in analytes' mobilities during electrophoresis, resulting in narrowing of their bands at the boundary. Around 550-1000-fold sensitivity enhancement could be achieved in terms of peak intensity without degrading peak shape and resolution. This technique is easy to perform and will be useful for peptide mass fingerprinting in protein analysis.
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Affiliation(s)
- Koshi Imami
- Graduate School of Material Science, University of Hyogo, Kamigori, Hyogo 678-1297, Japan.
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26
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Shiddiky MJA, Shim YB. Trace Analysis of DNA: Preconcentration, Separation, and Electrochemical Detection in Microchip Electrophoresis Using Au Nanoparticles. Anal Chem 2007; 79:3724-33. [PMID: 17428034 DOI: 10.1021/ac0701177] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have developed a simple and sensitive on-chip preconcentration, separation, and electrochemical detection (ED) method for trace analysis of DNA. The microchip comprised of three parallel channels: the first two are for the field-amplified sample stacking and subsequent field-amplified sampled injection steps, while the third one is for the microchip gel electrophoresis (MGE) with ED (MGE-ED). To improve preconcentration and separation performances of the method, the stacking and separation buffers containing the hydroxypropyl cellulose (HPC) matrix were modified with gold nanoparticles (AuNPs). The formation of AuNPs and HPC/AuNP-modified buffers were characterized by UV-visible spectroscopy and TEM experiments. The conducting polymer-modified electrode was also modified with AuNPs to enhance detection performances of the electrode. The conducting polymer/AuNP layers act as electrocatalysts for the direct detection of DNA based on their oxidation in a solution phase. The total sensitivity was improved by approximately 25 000-fold when compared with a conventional MGE-ED analysis. The calibration plots were linear (r2 = 0.9993) within the range of 0.003-1.0 pg/microL for a 20-bp DNA sample. The sensitivity was 0.20 nA/(fg/microL), with a detection limit of 5.7 amol in a 50-microL sample, based on S/N = 3. The applicability of the method for the analysis of 13 fragments present in a 100-bp DNA ladder was successfully demonstrated.
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Affiliation(s)
- Muhammad J A Shiddiky
- Department of Chemistry, Pusan National University, Keumjeong-ku, Busan 609-735, South Korea
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27
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Wang H, Lu M, Le XC. DNA-driven focusing for protein-DNA binding assays using capillary electrophoresis. Anal Chem 2007; 77:4985-90. [PMID: 16053313 DOI: 10.1021/ac050342t] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A DNA-driven focusing technique is reported for protein-DNA binding assays using capillary electrophoresis. A fluorescent DNA aptamer of 84 nucleotides (RT12) was used to bind to a specific protein, human immunodeficiency virus type 1 reverse transcriptase. The aptamer-protein complexes were effectively focused, separated by capillary electrophoresis, and detected by laser-induced fluorescence (LIF). With this DNA-driven focusing, the separation efficiency of the aptamer-protein complex reached 5 million theoretical plates/m, and the sensitivity for the detection of this complex was improved by 70-120-fold. The DNA-driven focusing technique was further applied to protein-DNA binding assays and to enhance the detection of DNA adducts. DNA adducts present in short oligonucleotides or genomic DNA were recognized by and bound to specific antibodies, and the complexes were focused electrophoretically and detected by LIF. The results demonstrate that the DNA-driven focusing can improve separation, sensitivity, and speed of analysis. The focusing is tolerant to high-salt medium, which is usually necessary to support physiological protein-DNA binding. This technique may be applied to nucleic acid analysis, aptamer affinity analysis, immunoassays for DNA damage, and DNA/RNA based binding assays.
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Affiliation(s)
- Hailin Wang
- Department of Public Health Sciences, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2G3, Canada
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28
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Breadmore MC. Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips. Electrophoresis 2007; 28:254-81. [PMID: 17149782 DOI: 10.1002/elps.200600463] [Citation(s) in RCA: 160] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Poor sensitivity is considered to be one of the major limitations of electrophoretic separation methods, particularly when compared to traditional liquid chromatographic techniques. To address this issue, various in-line preconcentration techniques have been developed over the past 15 years, ranging in power and complexity, and there are now a number of well understood approaches routinely capable of providing a 10,000- to 100,000-fold increase in sensitivity, as well as several that can be pushed above a million. Furthermore, these have been achieved with particularly troublesome and often difficult samples, such as those having high salinity from a biological or environmental origin. This review will discuss the most common methods for improving the sensitivity of CE, CEC and microchip version of these, with particular attention to those approaches developed over the last five years.
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Affiliation(s)
- Michael C Breadmore
- Australian Centre for Research on Separation Science, School of Chemistry, University of Tasmania, Hobart, Tasmania, Australia.
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29
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Qu Q, Liu Y, Tang X, Wang C, Yang G, Hu X, Yan C. Etched bare fused-silica capillaries for online preconcentration of amino acids in CE. Electrophoresis 2007; 27:4500-7. [PMID: 17054084 DOI: 10.1002/elps.200600057] [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: 11/06/2022]
Abstract
An online preconcentration method based on electrostatic interaction between the analytes and inner surface of the capillary column was developed for the determination of zwitterionic analytes such as amino acids in CE coupled with a DAD. The amino acids possessed positive charges when they were dissolved in an acidic solvent. When they were injected into the column, they were attracted by the negatively charged inner surface of the fused-silica capillary column. An etched column was used to increase the area of the capillary's inner surface and, consequently increase the electrostatic interaction between the amino acids and the inner surface of the capillary column. It was found that when the sample was injected at 10 psi for 1 min and the pH value of the sample was 4, the amount of amino acids attracted to the inner surface of the capillary was maximum. Under these optimized experimental conditions, the detection sensitivity of CE-DAD was enhanced by 5200, 2800, and 3100 times for asparagine, tryptophan and phenylalanine, respectively, compared with normal CE separation. The method provided good reproducibility in terms of both migration time and peak height. It can be successfully used for the preconcentration zwitterion.
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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, P. R. China.
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30
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Wan F, He W, Zhang J, Ying Q, Chu B. Scale-up development of high-performance polymer matrix for DNA sequencing analysis. Electrophoresis 2006; 27:3712-23. [PMID: 16960843 DOI: 10.1002/elps.200600299] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Linear polyacrylamide (LPA) has been widely used as a replaceable separation matrix in CE. An increase in the molecular weight of the separation medium favors the separation of larger DNA fragments. In order to obtain ultrahigh-molecular-weight (UHMW) LPA, a "frozen" method was developed to synthesize the LPA homopolymer. This approach has three major advantages when compared with other existing routes of LPA synthesis: (i) long LPA chains could be obtained easily, with their average molecular weight (MW) being in the high 10 MDa range; (ii) the desired MW could be adjusted over a broad range by controlling the temperature and the concentration of initiators during synthesis; (iii) the product solution contains only a tiny amount of impurity besides the solvent and LPA. Both static and dynamic laser light scattering measurements were carried out to characterize the synthesized LPA in the buffer solution. The DNA sequencing matrix prepared from LPA using this method was studied and the results were compared with the newly developed commercial product POP7 from Applied Biosystems. It should be noted that this approach can be applied to synthesize other water-soluble polymers, resulting in UHMW products because the chain transfer constant is smaller at lower temperatures.
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Affiliation(s)
- Fen Wan
- Department of Chemistry, Stony Brook University, Stony Brook, NY, USA
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31
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Lin YW, Chang HT. Analysis of double-stranded DNA by capillary electrophoresis using poly(ethylene oxide) in the presence of hexadecyltrimethylammonium bromide. J Chromatogr A 2006; 1130:206-11. [PMID: 16597443 DOI: 10.1016/j.chroma.2006.03.050] [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] [Received: 01/09/2006] [Revised: 03/01/2006] [Accepted: 03/17/2006] [Indexed: 01/23/2023]
Abstract
The impact of hexadecyltrimethylammonium bromide (CTAB) on the separation of ds-DNA by capillary electrophoresis in conjunction with laser-induced fluorescence (CE-LIF) detection using poly(ethylene oxide) (PEO) solution is described. The use of CTAB for improved separation reproducibility and efficiency of DNA has not been demonstrated although it is widely used for controlling the magnitude and direction of electroosmotic flow in CE. With increasing CTAB concentration, the interactions of DNA with ethidium bromide (EtBr) and with the capillary wall decrease. For the separation of DNA fragments with the sizes ranging from several base pairs (bp) to 2,176 bp, a polymer solution consisting of 0.75% poly(ethylene oxide), 100 mM TB buffer (pH 8.0), 25 microg/mL EtBr, and 0.36 microg/mL CTAB is proper. Using the PEO solution, we separated a mixture of DNA markers V (pBR 322/HaeIII digest) and VI (pBR 328/BglI digest and pBR 328/HinfI digest) within 8 min at -375 V/cm, with the limit of detection of 2.0 ng/mL based on the peak height for the 18-bp DNA fragment. The method is highly efficient (>10(6)plate/m), repeatable (RSD of the migration times <1.5%), and sensitive. In addition, it is convenient to fill a capillary (75 microm in diameter) with such a low-viscosity PEO solution by syringe pushing.
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Affiliation(s)
- Yang-Wei Lin
- Department of Chemistry, National Taiwan University, Section 4, Roosevelt Road, Taipei, Taiwan, ROC
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32
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Korir AK, Almeida VK, Larive CK. Visualizing Ion Electromigration during Isotachophoretic Separations with Capillary Isotachophoresis-NMR. Anal Chem 2006; 78:7078-87. [PMID: 17037906 DOI: 10.1021/ac061431o] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Sample stacking techniques in electrophoresis are gaining popularity due to their ability to provide improved sensitivity and separation efficiency. The principles behind sample stacking and electrophoretic migration have been studied extensively. Nevertheless, there are still a number of observations and descriptions of ionic boundaries and migration modes for which the underlying principles are not yet fully understood. For example, the behavior of capillary isotachophoresis (cITP) systems that exhibit self-sharpening effects can be complex, especially when the buffer systems contain many ionic components. In this work, cITP coupled with 1H NMR detection is used to study electrophoretic migration of ions in both anionic and cationic cITP. A significant advantage of 1H NMR over other detection methods is the high specificity of this method, allowing detection of individual buffer and analyte constituents within the migration zones.
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Affiliation(s)
- Albert K Korir
- Department of Chemistry, University of California, Riverside, California 92521, USA
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33
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Fang H, Zeng Z, Liu L. Centrifuge Microextraction Coupled with On-Line Back-Extraction Field-Amplified Sample Injection Method for the Determination of Trace Ephedrine Derivatives in the Urine and Serum. Anal Chem 2006; 78:6043-9. [PMID: 16944882 DOI: 10.1021/ac060360q] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Although sample stacking has enjoyed some degree of success in electrophoretic separation techniques, there is still a major problem with complex matrix sample as it suffers tremendously from sample matrix effects. A novel method that combines two concentration techniques, centrifuge microextraction (CME) and on-line back-extraction field-amplified sample injection (OLBE-FASI), is used to determine trace ephedrine derivatives in urine and serum by capillary zone electrophoresis. The CME, integrating the sample cleanup and preconcentration into a single step, is a promising sample preparation method for biological samples. The CME technique provided 9-14-fold enrichment within 10 min. The OLBE-FASI eliminated the need to perform solvent exchange and provided a further concentration of the analytes. Using CME coupled with OLBE-FASI, over a 3800-fold increase in sensitivity could be obtained as compared with the normal hydrodynamic injection without sample stacking. For a 1-mL urine sample, the linear range was 5/10-200 ng/mL with the square of the correlation coefficients (r(2)) ranging from 0.9988 to 0.9994. Detection limits were from 0.15 to 0.25 ng/mL using a photodiode array UV detection at wavelength 192 nm. The possibility of this method to determine ephedrine derivatives in 20-muL serum samples was also demonstrated.
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Affiliation(s)
- Huaifang Fang
- Department of Chemistry, Wuhan University, Wuhan 430072, China
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34
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Zhang ZX, He YZ, Hu YY. On-line sequential preconcentration of inorganic anions by anion-selective exhaustive injection and base-stacking in capillary zone electrophoresis. J Chromatogr A 2006; 1109:285-90. [PMID: 16478625 DOI: 10.1016/j.chroma.2006.01.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2005] [Revised: 12/29/2005] [Accepted: 01/10/2006] [Indexed: 11/24/2022]
Abstract
A sequential electrostacking method based on anion-selective exhaustive injection (ASEI) and base-stacking (BS) is presented for the preconcentration and determination of inorganic anions by capillary zone electrophoresis (CZE) in this paper. Tetradecyltrimethylammonium bromide as an electroosmotic flow (EOF) modifier was added into the buffer to suppress EOF of the capillary. Firstly, a water plug was hydrodynamically injected into the capillary. During ASEI under negative high voltage, the sample anions migrated quickly towards the boundary between the water plug and buffer in the capillary. Then an alkaline zone was injected electrokinetically to concentrate the anions further. With the sequential electrostacking method, the preconcentration factor of (0.8-1.3) x 10(5) was obtained compared with the conventionally electrokinetic injection and the relative standard deviation of peak area was 3.3-5.3% (n = 5). The detection limits of ASEI-BS-CZE for six inorganic anions were 6-14 ng/L. The proposed method has been adopted to analyze six anions in cigarette samples successfully.
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Affiliation(s)
- Zhao-Xiang Zhang
- Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China
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35
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Chang YS, Shih CM, Li YC, Lin CH. Large-Volume Sample Sweeping with a High Theoretical Plate Number Using a Coupled-Capillary in Capillary Electrophoresis. ANAL SCI 2006; 22:557-61. [PMID: 16760597 DOI: 10.2116/analsci.22.557] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A large-volume sample injection (> 5 microL) with an extremely high theoretical plate number (N > 10(7)) was achieved when the sweeping-MEKC mode and a coupled-capillary (100 - 50 microm i.d.) were simultaneously used in a capillary electrophoresis (CE) separation. A low-cost and compact violet-LED ( approximately 2 mW) was used as the fluorescence excitation source. As a result, the theoretical plate numbers of the detected peaks (two model compounds: naphthalene-2,3-dicarboxaldehyde derivatized-dopamine and -norepinephrine) were 1.0 x 10(7) and 7.4 x 10(6), respectively. The limits of detection (at S/N = 3) of these were determined to be 2.8 x 10(-10) M (92 ppt) and 2.3 x 10(-10) M (83 ppt), respectively.
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Affiliation(s)
- Yen-Sheng Chang
- Department of Chemistry, National Taiwan Normal University, Taipei, Taiwan
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36
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Zhang LY, Sun MX. Field-amplified sample injection and in-capillary derivatization for sensitivity improvement of the electrophoretic determination of histamine. J Chromatogr A 2005; 1100:230-5. [PMID: 16212971 DOI: 10.1016/j.chroma.2005.09.041] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2005] [Revised: 09/14/2005] [Accepted: 09/19/2005] [Indexed: 11/17/2022]
Abstract
The feasibility of the combination of field-amplified sample injection (FASI) and in-capillary derivatization was explored for improving sensitivity of histamine in capillary electrophoresis (CE). Naphthalene-2,3-dicarboxaldehyde (NDA) was used as derivatization reagent. The reagent and sample was introduced by tandem mode. The derivatization was accomplished by at-inlet mode with standing time of 1.5 min. The combination of FASI and in-capillary derivatization was successfully achieved with about 400-fold concentration sensitivity enhancement compared to pre-capillary derivatization at the same set-up. The detection limit of concentration for histamine reached 1.25 x 10(-11) M by CE and fluorescence detection with S/N = 3. Parameters affecting FASI and in-capillary derivatization process including sample matrix, buffer concentration and reagent injection amount, were investigated.
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Affiliation(s)
- Li-Yao Zhang
- Key Laboratory of MOE for Plant Development Biology, College of Life Sciences, Wuhan University, China
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37
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Shih CM, Lin CH. Low-temperature bath/coupled-capillary/sweeping-micellar electrokinetic capillary chromatography for the separation of naphthalene-2,3-dicarboxaldehyde-derivatized dopamine and norepinephrine. Electrophoresis 2005; 26:2165-71. [PMID: 15861464 DOI: 10.1002/elps.200510409] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The use of a low-temperature (0 degrees C) bath-assisted coupled capillary for the separation of naphthalene-2,3-dicarboxaldehyde (NDA)-derivatized dopamine and norepinephrine using the sweeping-micellar electrokinetic capillary chromatography (MEKC) mode is described. In this technique, a capillary consisting of two portions with different inside diameters is used. Therefore, the field strength inside the capillary is different. Hence, the electrophoretic migration velocities of the analytes and the electro-osmotic flow (EOF) also are different. Furthermore, when a portion of the capillary (wide portion, used for sweeping) is immersed in a low-temperature bath, the viscosity of the buffer and the retention factor of the analytes inside are increased. Thus, not only are the interactions between the SDS micelles and the analytes increased, but the SDS-analytes also move more slowly. As a result, a more complete separation can be achieved, even when the sample injection volume is large, up to approximately 2 microL. In general, when the volume of an injected sample is larger, the effects of sweeping and separation would become insufficient, especially when the retention values (k) of the analytes are quite different. However, this limitation can be improved when the low-temperature bath/coupled capillary/sweeping-MEKC mode is used.
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Affiliation(s)
- Chun-Min Shih
- Department of Chemistry, National Taiwan Normal University, Taipei, Taiwan
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38
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Monton MRN, Imami K, Nakanishi M, Kim JB, Terabe S. Dynamic pH junction technique for on-line preconcentration of peptides in capillary electrophoresis. J Chromatogr A 2005; 1079:266-73. [PMID: 16038313 DOI: 10.1016/j.chroma.2005.03.069] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A method based on the presence of a dynamic pH junction within the capillary to induce band narrowing for enhanced detection sensitivity for some peptides is presented. This technique is predicated on a sharp reduction in an analyte's migration velocity following a reversal of its electrophoretic direction from the acidic sample zone to the basic BGS zone. Larger-than-usual injection volumes of samples in relatively high-conductivity matrices were enabled, without degrading peak shape, resolution and efficiency. The size of the original sample plug was reduced by as much as 38-fold, and improvement in detector response in terms of peak height by as much as 124-fold was obtained. The effects of pH and concentration of the sample matrix, and the length of sample injection on the efficiency of the technique are discussed.
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Affiliation(s)
- Maria Rowena N Monton
- Graduate School of Material Science, University of Hyogo, Kamigori, Hyogo 678-1297, Japan.
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39
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Buch JS, Rosenberger F, Highsmith WE, Kimball C, DeVoe DL, Lee CS. Denaturing gradient-based two-dimensional gene mutation scanning in a polymer microfluidic network. LAB ON A CHIP 2005; 5:392-400. [PMID: 15791336 DOI: 10.1039/b416682e] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
An integrated two-dimensional (2-D) DNA separation platform, combining standard gel electrophoresis with temperature gradient gel electrophoresis (TGGE) on a polymer microfluidic chip, is reported. Rather than sequentially sampling DNA fragments eluted from standard gel electrophoresis, size-resolved fragments are simultaneously electrokinetically transferred into an array of orthogonal microchannels and screened for the presence of sequence heterogeneity by TGGE in a parallel and high throughput format. A bulk heater assembly is designed and employed to externally generate a temporal temperature gradient along an array of TGGE channels. Extensive finite element modeling is performed to determine the optimal geometries of the microfluidic network for minimizing analyte band dispersion caused by interconnected channels in the network. A pH-mediated on-chip analyte stacking strategy is employed prior to the parallel TGGE separations to further reduce additional band broadening acquired during the electrokinetic transfer of DNA fragments between the first and second separation dimensions. A comprehensive 2-D DNA separation is completed in less than 5 min for positive detection of single-nucleotide polymorphisms in multiplex PCR products that vary in size and sequence.
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Affiliation(s)
- Jesse S Buch
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
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40
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Tsai CH, Tsai CC, Liu JT, Lin CH. Sample-stacking techniques in non-aqueous capillary electrophoresis. J Chromatogr A 2005; 1068:115-21. [PMID: 15844549 DOI: 10.1016/j.chroma.2004.12.095] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
In sample-stacking techniques, the detection limit cannot be improved by simply increasing the length of the sample solution, because the individual electrophoretic parameters must be optimized. In an attempt to increase the amount of sample injected, as well as to focus them onto a small zone, two novel methods are proposed. One of these employs an "ultra-high conductivity zone", which was inserted between the sample zone and background solution to build an unequal conductivity gradient. The other employs a "low temperature bath". A portion of the capillary (near the junction between the sample solution and the background solution) was immersed in a low temperature bath, which served as a "pseudo-high-conductivity zone" due to the fact that conductivity would increases when the temperature is decreased. As a result, a large volume of sample injection can be achieved. Using 3,4-methylenedioxymethamphetamine as a model compound, the detection limit was determined to be 1.6 x 10(-6) M (S/N = 3) by means of normal non-aqueous capillary electrophoresis (NACE). This could be improved to 3.0 x 10(-8) M, 4.8 x 10(-9) M and 5.0 x 10(-9) M, respectively, when the normal stacking, ultra-high conductivity zone NACE-stacking and the low-temperature zone NACE-stacking methods were applied.
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Affiliation(s)
- Chih-Hsin Tsai
- Department of Chemistry, National Taiwan Normal University, 88 Sec. 4, Tingchow Road, Taipei, Taiwan
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41
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Zhang ZX, He YZ. On-line cation-exchange preconcentration and capillary electrophoresis coupled by tee joint interface. J Chromatogr A 2005; 1066:211-8. [PMID: 15794573 DOI: 10.1016/j.chroma.2005.01.081] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
An on-line preconcentration method based on ion exchange solid phase extraction was developed for the determination of cationic analytes in capillary electrophoresis (CE). The preconcentration-separation system consisted of a preconcentration capillary bonded with carboxyl cation-exchange stationary phase, a separation capillary for zone electrophoresis and a tee joint interface of the capillaries. Two capillaries were connected closely inside a 0.3 mm i.d. polytetrafluoroethylene tube with a side opening and fixed together by the interface. The preparations of the preconcentration capillaries and interface were described in detail in this paper. The on-line preconcentration and separation procedure of the analysis system included washing and conditioning the capillaries, loading analytes, filling with buffer solution, eluting analytes and separating by capillary zone electrophoresis (CZE). Several analysis parameters, including sample loading flow rate and time, eluting solution and volume, inner diameter and length of preconcentration capillary etc., were investigated. The proposed method enhanced the detection sensitivity of CE-UV about 5000 times for propranolol and metoprolol compared with normally electrokinetic injection. The detection limits of propranolol and metoprolol were 0.02 and 0.1 microg/L with the proposed method respectively, whereas those were 0.1 and 0.5 mg/L with conventional electrokinetic injection. The experiment results demonstrate that the proposed technique can increase the preconcentration factor evidently.
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Affiliation(s)
- Zhao-Xiang Zhang
- Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, PR China
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42
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Huang HM, Lin CH. Methanol plug assisted sweeping-micellar electrokinetic chromatography for the determination of dopamine in urine by violet light emitting diode-induced fluorescence detection. J Chromatogr B Analyt Technol Biomed Life Sci 2005; 816:113-9. [PMID: 15664341 DOI: 10.1016/j.jchromb.2004.11.018] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2004] [Accepted: 11/09/2004] [Indexed: 12/01/2022]
Abstract
The use and limitations of a methanol plug assisted sweeping-micellar electrokinetic chromatography (sweeping-MEKC) method is described. Using naphthalene-2,3-dicarboxaldehyde (NDA)-labeled dopamine as a model compound, this new method was also used in the determination of dopamine in actual urine samples. An inexpensive violet light emitting diode (LED) was used for the light source, because this is suitable for fluorescence excitation. The number of theoretical plates of the analyte was determined to be approximately 1 x 10(5) and approximately 2 x 10(5) by means of MEKC and sweeping-MEKC and this was improved to approximately 1 x 10(6) when the methanol plug assisted mode was applied. In addition, the detection limit of NDA-labeled dopamine was determined to be 9.1 x 10(-7) and 1.2 x 10(-8)M by means of MEKC and sweeping-MEKC and this was improved to 4.7 x 10(-9)M when the methanol plug assisted sweeping-MEKC mode was applied.
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Affiliation(s)
- Hsuan-Ming Huang
- Department of Chemistry, National Taiwan Normal University, 88 Sec. 4, Tingchow Road, Taipei, Taiwan
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43
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Shih CM, Lin CH. Comparison of the use of single capillaries and coupled capillaries based on micellar electrokinetic chromatography (MEKC) and sweeping-MEKC modes. Electrophoresis 2005; 26:962-969. [PMID: 15669011 DOI: 10.1002/elps.200410189] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The use of single capillaries (25 and 50 microm inner diameter (ID)) and coupled capillaries of different diameters (100-50 and 75-25 microm ID) based on micellar electrokinetic chromatography (MEKC) and sweeping-MEKC modes is compared and reported. Naphthalene-2,3-dicarboxaldehyde (NDA)-derivatized dopamine was selected as the model compound by examining the fluorescence intensity when a violet (410 +/- 7 nm, 2 mW) light-emitting-diode (LED) was used as the light source. When a single capillary (50 microm ID) was used, the detection limit for NDA-derivatized dopamine was determined to be 2.0 x 10(-7) M (Signal-to-nose ratio S/N = 3) based on the MEKC mode. This was improved to 4.0 x 10(-9) M when the sweeping-MEKC mode was applied. In addition, this can be further improved to 1.0 x 10(-9) M and 5.6 x 10(-10) M when 100-50 and 75-25 microm ID coupled capillaries are used. The use of the coupled capillary is also helpful for improving the separation efficiency. Based on the sweeping-MEKC mode, the number of theoretical plates (N) for the detected peaks were determined to be 6.3 +/- 2.7 x 10(5) by means of a single capillary (50 microm ID). This can be improved to 9.4 +/- 3.6 x 10(5) and 9.4 +/- 0.9 x 10(6) when the 100-50 and 75-25 microm ID coupled capillaries were applied.
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Affiliation(s)
- Chun-Min Shih
- Department of Chemistry, National Taiwan Normal University, Taipei, Taiwan
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44
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Kim DK, Kang SH. On-channel base stacking in microchip capillary gel electrophoresis for high-sensitivity DNA fragment analysis. J Chromatogr A 2005; 1064:121-7. [PMID: 15729827 DOI: 10.1016/j.chroma.2004.12.045] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We evaluated a novel strategy for high-sensitivity DNA fragment analysis in a conventional glass double-T microfluidic chip. The microchip allows for a DNA on-channel concentration based on base stacking (BS) with a microchip capillary gel electrophoretic (MCGE) separation step in a poly(vinylpyrrolidone) (PVP) sieving matrix. Depending if low conductivity caused a neutralization reaction between the hydroxide ions and the run buffer component Tris+, the stacking of DNA fragments were processed in the microchip. Compared to a conventional MCGE separation with a normal electrokinetic injection, the peak heights of 50-2650-base pair (bp) DNA fragments on the MCGE-BS separation were increased 3.9-8.0-fold. When we applied the MCGE-BS method to the analysis of a clinical sample of bovine theileria after PCR reaction, the peak height intensity of the amplified 816-bp DNA fragment from the 18S rRNA of T. buffeli was enhanced 7.0-fold compared to that of the normal injection method.
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Affiliation(s)
- Dae-Kwang Kim
- Department of Chemistry, Chonbuk National University, Jeonju 561-756, South Korea
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45
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On-line sample preconcentration techniques in capillary electrophoresis. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/s0166-526x(05)45003-5] [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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46
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Park SR, Swerdlow H. Concentration of DNA in a Flowing Stream for High-Sensitivity Capillary Electrophoresis. Anal Chem 2003; 75:4467-74. [PMID: 14632051 DOI: 10.1021/ac034209h] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A novel sample pretreatment device is described, and its application to the concentration and purification of crude DNA samples in a flowing stream for subsequent capillary electrophoresis is demonstrated. The device consists of two gap junctions, each covered with a conductive membrane material and built upon a flow channel made of PEEK tubing. Upon the application of an electric field between the junctions, the negatively charged DNA fragments can resist the hydrodynamic flow stream and are trapped between the junctions. DNA fragments dissolved in microliter volumes are captured in a nanoliter-sized band by simply pushing the sample solution through the device. Depending on their electrophoretic mobility, other interfering materials in a crude sample can be removed from the trapped DNA fragments by washing. The selective permeability of the membrane to small ions allows efficient desalting. The concentrated and purified DNA fragments are released by simply turning off or reversing the electric field. Recovery is up to 95%. Performance of the device was evaluated using crude products of fluorescent dye-primer cycle-sequencing reactions. Compared to these crude reaction products, samples purified in the capture device and subsequently collected showed dramatically enhanced signal and resolution when run on a conventional capillary-electrophoresis instrument. Furthermore, the device could be connected in-line to a capillary system for direct injection. The device has great potential for enabling lab-on-a-chip systems to be used with real-world samples.
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Affiliation(s)
- Sang-Ryoul Park
- Department of Human Genetics, University of Utah, 20 S. 2030 E., Room 308, Salt Lake City, Utah 84112-9454, USA.
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47
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Vreeland WN, Williams SJ, Barron AE, Sassi AP. Tandem isotachophoresis-zone electrophoresis via base-mediated destacking for increased detection sensitivity in microfluidic systems. Anal Chem 2003; 75:3059-65. [PMID: 12964751 DOI: 10.1021/ac0259921] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Electrophoresis in microfluidic devices is becoming a useful analytical platform for a variety of biological assays. In this report, we present a method that allows for an increased sensitivity of detection of fluorescent molecules in microfluidic electrophoresis devices. This capability is provided by the implementation of a particular buffer system that is designed to initially function in an isotachophoretic (ITP) mode and, then after a controlled amount of electric current has been applied to the system, to transition to a zone electrophoretic mode. In the initial ITP mode, analytes dissolved in a large volume of injected sample are concentrated into a single narrow zone. After application of a sufficient and adjustable amount of electric current, the system switches into a zone electrophoretic mode, where the concentrated analytes are separated according to their electrophoretic mobilities. Application of this tandem ITP-zone electrophoretic strategy to the concentration, separation, and detection of fluorescent reporter molecules in a standard microfluidic device results in an approximately 50-fold increase in detection sensitivity relative to equivalent separations that are obtained with zone electrophoresis alone. Even with very long initial sample plugs (up to 3000 microm), this strategy produces electrophoretic separations with high resolutions and peak efficiencies. This strategy can be implemented to increase detection sensitivity in any standard microfluidic electrophoresis platform and does not require any specialized hardware or microchannel configurations.
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Britz-McKibbin P, Terabe S. On-line preconcentration strategies for trace analysis of metabolites by capillary electrophoresis. J Chromatogr A 2003; 1000:917-34. [PMID: 12877205 DOI: 10.1016/s0021-9673(03)00502-8] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Analysis of low concentrations of metabolites is required for new fields of biological research, such as metabolomics. In this review, recent work in our laboratory aimed at developing improved strategies for on-line sample preconcentration of metabolites by capillary electrophoresis (CE) is presented. Dynamic pH junction, sweeping and dynamic pH junction-sweeping represent three complementary methods for electrokinetic focusing of large volumes of sample directly on-capillary. Focusing selectivity and focusing efficiency are two factors that can be used to assess the suitability of each method for different classes of metabolites. Buffer properties can be selected to enhance the focusing of specific types of metabolites based on knowledge of the analyte physicochemical properties. The application of on-line preconcentration CE for trace analysis of metabolites in real samples of interest, such as biological fluids and cellular extracts, is also demonstrated. Under optimum conditions, up to three orders of magnitude increase in concentration sensitivity can be realized for several classes of metabolites, including catecholamines, purines, nucleosides, nucleotides, amino acids, steroids and coenzymes. Recent work on hyphenating on-line preconcentration with multiplexed CE is highlighted as a promising platform for sensitive and high-throughput analyses of metabolites.
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Affiliation(s)
- Philip Britz-McKibbin
- Graduate School of Science, Himeji Institute of Technology, Kamigori, Hyogo 678-1297, Japan.
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Arnett SD, Lunte CE. Investigation of the mechanism of pH-mediated stacking of anions for the analysis of physiological samples by capillary electrophoresis. Electrophoresis 2003; 24:1745-52. [PMID: 12783451 PMCID: PMC2519817 DOI: 10.1002/elps.200305399] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Capillary electrophoresis has been widely used for the analysis of physiological samples such as plasma and microdialysate. However, sample destacking can occur during the analysis of these high-ionic strength samples, resulting in poor separation efficiency and reduced sensitivity. A technique termed pH-mediated stacking of anions (base stacking) has previously been developed to analyze microdialysate samples and achieve on-line preconcentration of analytes by following sample injection with an injection of sodium hydroxide. In this work, the mechanism of base stacking was investigated. Peak efficiency was shown to be a function of background electrolyte and sample ionic strength. Analytes representing several classes of compounds with a wide range of mobilities were used to study the effects of multiple parameters on sample stacking. The length of hydroxide injection required for stacking was shown to be dependent on analyte mobility and the type of amine background electrolyte used. Combinations of electrokinetic and hydrodynamic injections of sample and hydroxide were examined and it was concluded that although stacking could be achieved with several injection modes, electrokinetic injection of both sample and hydroxide was most effective for sample stacking. The mechanism of pH-mediated stacking for each of these modes is presented.
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Affiliation(s)
- Stacy D Arnett
- Department of Chemistry, University of Kansas, Lawrence, KS, USA
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Lin YW, Huang CC, Chang HT. Capillary electrophoretic separation of dsDNA under nonuniform electric fields. Anal Bioanal Chem 2003; 376:379-83. [PMID: 12719958 DOI: 10.1007/s00216-003-1906-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2003] [Revised: 03/10/2003] [Accepted: 03/11/2003] [Indexed: 11/29/2022]
Abstract
Improved sensitivity for the analysis of DNA by capillary electrophoresis has been achieved, based on simultaneous increases in optical path length and injection volume. To increase the optical path length, bubble cells with diameters ranging from 150 to 450 microm have been fabricated and tested. In terms of resolution and sensitivity, a bubble cell of 300 microm diameter is appropriate when using 75-microm capillaries. To allow greater injection volumes, we performed on-line concentration of DNA in the presence of electroosmotic flow (EOF) using 2.0% poly(ethylene oxide) (PEO). With a 300-microm bubble cell, a 170-fold improvement in the sensitivity for the 89-bp fragment has been accomplished when injecting about 0.33 microL DNA. In the presence of the bubble cell, the resolution for the large fragments improves while that for the small ones (<124 base pair) decreases. The effect of bubble cells was further investigated by conducting DNA separation in the absence of EOF, showing that improvements in resolution are mainly due to increased migration differences when DNA migrated at low electric field strengths in the bubble region. We have suggested that such an effect is more profound using shorter capillaries, leading to complete separation of phiX 174 RF DNA-Hae III digest in 2 min.
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Affiliation(s)
- Yang-Wei Lin
- Department of Chemistry, National Taiwan University, Section 4, Roosevelt Road, Taipei, R.O.C
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