Sensitivity enhancement for capillary electrophoresis

Albin, Michael; Grossman, Paul D.; Moring, Stephen E.

doi:10.1021/ac00058a002

Cited by 186 publications

(93 citation statements)

References 20 publications

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“…Nevertheless, the use of this sort of columns is actually not applied much in capillary electrophoresis because the disadvantages that they present compared with cylindrical columns. These disadvantages can be summarized as: a) several technical problems associated with the practical development of rectangular capillaries [15,16], b) the necessity of optimizing both the optics and the orientation of the rectangular capillary for efficient radiation throughput [16], c) wall thickness has a greater influence on temperature gradients for rectangular sections than in cylindrical ones [17]. However, rectangular columns also present a large number of advantages that make them very interesting for their use in capillary electrophoresis especially when the separation of larger quantities is required.…”

Section: Introductionmentioning

confidence: 99%

Rectangular capillary electrophoresis: Some theoretical considerations

Cifuentes

Poppe

1994

Chromatographia

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SummaryA theoretical study of the use of rectangular columns in capillary electrophoresis (CE) is presented. It was done employing some of the most important parameters that normally define the performance of CE separations, i.e. thermal effect, analysis speed, efficiency and sample capacity. Theoretical results from rectangular and cylindrical capillaries are compared in terms of the aforementionated parameters. Also, an estimate of the additional zone broadening that arises from the noninfinite dimension in the y-direction, in which the channel has its largest dimension, is presented.

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Section: Introductionmentioning

confidence: 99%

Rectangular capillary electrophoresis: Some theoretical considerations

Cifuentes

Poppe

1994

Chromatographia

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“…When they reach the interface of the sample buffer and BGE, they slow down and stack into a narrower zone resulting in enhanced peak efficiency with increased peak height. Large volumes of sample can be injected producing up to a hundredfold concentration of cations oranions [8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

pH-Mediated field-amplified sample stacking of pharmaceutical cations in high-ionic strength samples

2001

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Capillary electrophoretic separation of samples of physiological origin typically have both poor resolution and efficiency due to destacking. We have previously reported a stacking method for concentration of catecholamines in artifical dialysate, or Ringer's solution. However, pH-mediated sample stacking of other cations has not been investigated. In this report, pH-mediated stacking has been extended to eletripan, dofetilide, doxazosin, sildenafil, UK-103,320, UK-202,581, and CP-122,288. These compounds were chosen without prior structural screening except that they were cationic at the pH of our background electrolyte (BGE). Capillary electrophoretic behavior of samples in BGE is compared with those of samples in Ringer's solution with and without pH-mediated acid stacking. Results indicate that the peak heights and efficiencies for acid-stacked samples are increased compared to the unstacked samples in Ringer's solution or BGE. For example, the peak efficiencies for 5 s injections of eletriptan in BGE and Ringer's solution are 138 000 and 72000 plates, respectively. In contrast, a 10 s injection of eletriptan followed by acid injection for 16 s produces a peak with 246 000 plates. Evaluation of the stacking effect was performed by comparison of the peak height at similar peak efficiencies for samples in Ringer's solution with and without stacking. Using this method, pH-mediated acid stacking provides a 10-to 27-fold sensitivity enhancement for the seven cations.

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“…The main limitation of CE is the relatively unfavorable concentration detection limits frequently obtained. Although mass detection limits are within the pmol to fmol range, the concentration detection limits are significantly higher because the injection and consequently the detection volumes are in the nL range (Albin et al, 1993). Linking CE to more sensitive detectors (eg MS, LIF) or the introduction of membrane pre-concentration could alleviate this problem (Guzman et al, 1997;MacTaylor and Ewing, 1997).…”

Section: Introductionmentioning

confidence: 99%

Determination of (3S)‐3‐hydroxy quinidine for metabolism screening experiments using direct injection capillary electrophoresis and laser‐induced fluorescence detection

Bhoopathy

Karnes

2001

Biomedical Chromatography

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Capillary electrophoresis (CE) has been used with collinear laser-induced fluorescence detection (LIF) to determine the amount of (3S)-3-hydroxy quinidine (3OHQ) formed on direct injection of microsomal incubation mixtures. 3OHQ is the CYP 3A4 metabolite of quinidine sulfate (QS) and is therefore useful for metabolism screening studies. The method was validated analytically and tested for its capability of screening for a weak inhibitor of the CYP 3A4 isozyme. A linear calibration was found to provide the best fit for the standard curve with a correlation of 0.9950 and all concentration residuals less than 15%. The percentage relative standard deviations (RSDs) of two controls, 175 and 2250 ng/mL, were 9.29 and 5.68% and the percentage differences from normal (DFN) were 6.87 and -4.37%, respectively. The concentration limit of detection (LOD) for 3OHQ in the incubation matrix was 52.11ng/mL and the mass LOD was approximately 521.1 fg (injection volume 10 nL). The effectiveness of the method to screen for the weak inhibitor erythromycin has been shown by calculating percentage inhibition when incubating with different concentrations of QS. Sensitive detection coupled with the convenience of the direct injection technique makes this an attractive approach for metabolism screening. The small sample size capability of CE will further reduce the quantities of probe drug, microsomes and other reagents required for incubation studies.

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Sensitivity enhancement for capillary electrophoresis

Cited by 186 publications

References 20 publications

Rectangular capillary electrophoresis: Some theoretical considerations

Rectangular capillary electrophoresis: Some theoretical considerations

pH-Mediated field-amplified sample stacking of pharmaceutical cations in high-ionic strength samples

Determination of (3S)‐3‐hydroxy quinidine for metabolism screening experiments using direct injection capillary electrophoresis and laser‐induced fluorescence detection

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