Origin and correction of bias caused by sample injection and detection in capillary zone electrophoresis

Moolen, J.N. van der; Boelens, H.F.M.; Poppe, H.; Smit, H.C.

doi:10.1016/0021-9673(96)00440-2

Cited by 29 publications

(11 citation statements)

References 26 publications

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“…To correct the detection bias, the observed peak area is corrected by dividing the peak area by the migration time of the peak, or by multiplying the peak area by the migration velocity of the peak, being sure to specify the units in either case. van der Moolen et al [40] suggested that the injection and detection bias are inversely proportional to each other during electrokinetic sample injections. Therefore, no correction of peak area is necessary for the bias in the case of electrokinetic injection being used in combination with UV detection.…”

Section: Sampling Bias and Correction Of Biasmentioning

confidence: 99%

Dual opposite injection electrokinetic chromatography: Nonionic microemulsion pseudostationary phase and novel approach to electrokinetic sampling bias

Zhou

Foley

2004

Electrophoresis

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Dual opposite injection capillary electrophoresis (DOI-CE) is a family of CE techniques in which the sample is introduced into both ends of the capillary. For the analysis of compounds with widely varying pKa values using a voltage-driven separation scheme, DOI-CE is superior to conventional CE with sample introduction at only one end of the capillary due to DOI-CE's broader elution window. To enhance the DOI-CE separation, a running buffer with a microemulsion system was developed. Since DOI-CE works best under conditions of low electroosmotic flow (EOF), the suppression of EOF via the addition of a multiply charged cation (e.g., Zn2+) to the buffer was investigated, and was found to suppress the EOF effectively at moderate concentrations (2.5-10 mM). Three different dual opposite injection modes were studied: simultaneous electrokinetic injection, sequential electrokinetic injection, and sequential hydrodynamic injection. The injection bias in the first two electrokinetic injection modes was compared with the sequential hydrodynamic injection. Corrections in the bias of the electrokinetic injections were discussed, and an improved approach was suggested. Finally, the effect of the relative concentration of the multiply charged cation in the sample plug and running buffer on the peak shape of co-electroosmotic and counter-electroosmotic ions was examined, and found to be much more influential on the latter.

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Section: Sampling Bias and Correction Of Biasmentioning

confidence: 99%

Dual opposite injection electrokinetic chromatography: Nonionic microemulsion pseudostationary phase and novel approach to electrokinetic sampling bias

Zhou

Foley

2004

Electrophoresis

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“…In CE the peaks do not all pass the detector at the same speed and, therefore, the more slowly-moving peaks spend more time in the detector, giving rise to larger peak areas. To obtain peak areas independent of time it is usual to divide these areas by the migration time; the areas thus calculated are designated normalized areas [28]. Normalized areas have been used in this study.…”

Section: Instrumentationmentioning

confidence: 99%

Determination of organic acids by capillary electrophoresis with simultaneous addition of Ca and Mg as complexing agents

2003

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SummaryA capillary electrophoretic method, with divalent cations as complexing agents in the electrolyte, has been developed for separation and determination of the low molecular weight organic acids most commonly found in wine, viz. formic, fumaric, succinic, oxalic, mahc, tartaric, acetic, lactic, and citric acids. The separation conditions optimized were electrolyte concentration, organic flow modifier concentration, type and concentration of complexing agents in the electrolyte, and injection time. The best resolution of some of the acids studied was achieved by use of an electrolyte containing tetraborate buffer (10 mM) at pH 9.3, an organic flow modifier (tetradecyltrimethylammonium hydroxide), and Ca 2+ (10 ppm) and Mg 2+ (10 ppm) as complexing agents. Other conditions used in the method were hydrostatic injection (10 cm height for 30 s), detection at 185 nm, and temperature 20 ~ For all the acids studied detector response was linear for the concentration ranges considered. The repeatability of each point on the calibration plot for standards (n = 4)was generally better than 1%. The method was applied to samples of must, wine, brandy, and vinegar from the Jerez region.

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“…Capillary electrophoresis: The normalized peak area (quotient between the peak area and the retention time) was used for quantification [26]. Although linearity in CE was lightly less than in ion-exclusion chromatography LOL values were always > 96% (Table II).…”

Section: Lol (%) = 100 Rds(b)mentioning

confidence: 99%

Comparative analysis of the organic acid content of vinegar by capillary electrophoresis and ion-exclusion chromatography with conductimetric detection

et al. 2002

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SummaryIon-exclusion chromatography (IEC) and capillary electrophoresis (CE) have been compared for determination of organic acids in samples of Sherry wine vinegar. The accuracy of each technique was evaluated by use of the standard addition method. There were no differences belvveen the techniques at a significance level of 5%, except for determination of malic acid by CE. Both analytical methods were used to analyse sixteen samples of Sherrywine vinegar supplied by different producers. The regression coefficients (r ~) for analysis by IEC and CE exceeded 0.94 for all acids. Results from both methods were in good agreement and the methods are sufficiently selective and sensitive to be applied directly to sherrywine vinegars.

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Origin and correction of bias caused by sample injection and detection in capillary zone electrophoresis

Cited by 29 publications

References 26 publications

Dual opposite injection electrokinetic chromatography: Nonionic microemulsion pseudostationary phase and novel approach to electrokinetic sampling bias

Dual opposite injection electrokinetic chromatography: Nonionic microemulsion pseudostationary phase and novel approach to electrokinetic sampling bias

Determination of organic acids by capillary electrophoresis with simultaneous addition of Ca and Mg as complexing agents

Comparative analysis of the organic acid content of vinegar by capillary electrophoresis and ion-exclusion chromatography with conductimetric detection

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