Interlaboratory reproducibility of mobility parameters in capillary electrophoresis for substance identification in systematic toxicological analysis

Abstract

An interlaboratory pilot study was performed to determine the reproducibility of mobility parameters in capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC). The study was performed by an intended small number of laboratories (three) that used different brands of instruments (two). The effective mobility was corrected using standards by a method that was recently introduced to obtain a more reproducible migration parameter. A test set of 20 acidic test compounds and 5 reference compounds were analyzed during five days in each laboratory using CZE and MEKC. Buffers used consisted of 90 mM borate set at pH 8.4 (CZE) and 20 mM phosphate, 50 mM sodium dodecyl sulfate set at pH 7.5 (MEKC). Analyses were carried out using fused-silica capillaries at an electric field strength of either 52.6 kV/m or 37.5 kV/m. The interlaboratory reproducibility (mean RSD) of the effective mobility was 3.0% for CZE and 6.7% for MEKC. After applying the correction method, these values became 3.0% for CZE and 3.3% for MEKC, which is adequate for systematic toxicological analysis (STA) applications. A significant improvement of reproducibility for the calculated corrected effective mobility mu(eff)c was observed when variations are high. Therefore, it is recommended to use the correction method in interlaboratory situations, especially when instruments and capillaries from different manufacturers are used.

Analysis of antiepileptic drugs in biological fluids by means of electrokinetic chromatography

“…To the best of our knowledge, only one MEKC method is reported in the literature for the analysis of acetazolamide in body fluids [55]. The proposed MEKC method is performed using a standard solution and it consists of an interlaboratory pilot study to determine the reproducibility of mobility parameters in CZE and MEKC.…”

Development of fully automated quantitative capillary electrophoresis with high accuracy and repeatability

“…The lack of a real injection valve in CE also leads to poor repeatability (i.e. low precision) in quantitative analyses (Boone et al, 2002;Smith et al, 1991). In addition, the discrimination effects from electrokinetic injection can be a problem for sample mixtures with different charges (Feng et al, 2007).…”

Double‐injection capillary electrophoresis for the identification of analytes

“…Another alternative to reduce the influence of the EOF on the migration velocity is to use the effective electrophoretic mobility (μ eff ), being independent of the electroosmotic mobility, as an identification parameter . To employ internal and/or external markers are yet another options for enhancing the reproducibility of the migration times and effective electrophoretic mobilities .…”