Wheat Varietal Identification by Capillary Electrophoresis: an Inter-Laboratory Comparison of Methods*

Capillary electrophoresis (CE) is a rapid automated method for wheat protein analysis. It is sensitive, reproducible, and gives high resolution separation ofgliadins, differentiating most genotypes. Optimal CE conditions have not yet been established, howevel; nor methods compared between laboratories. We therefore analysed gliadins from several varieties by two methods in two laboratories using comparable CE systems. A commercial 0.1 moUL phosphate buffel; pH 2.5, containing a linear hydrophilic polymer, was used with uncoated 27 cm silica capillaries (20 cm from inlet to detector) of50 and 20 WI! i.d. Separations with 50 pm capillaries were performed at 7 kV and required 30-40 min; those with 20 pm capillaries were performed at 22 kV, and separations took about 10 min. In each laboratory, both methods gave excellent separations, with comparable selectivity and resolution. For some analyses (especially those using 50 IInI capillaries), however, elution times and operating currents varied with different batches of commercial buffers, giving unacceptable reproducibility. TIllis, while CE is a useful alternative to slab gel electrophoresis or high performance liquid chromatography for wheat varietal identification, CE buffer compositions must be carefully controlled to ensure acceptable reproducibility.