Capillary electrophoresis method optimized with a factorial design for the determination of glutathione and amino acid status using human capillary blood

Plasma aromatic and sulfur containing amino acids are good indicators of protein anabolism/catabolism, while blood reduced and oxidized glutathione reflect oxidative status in an organism. Using a full factorial design for screening important variables (pH, concentration, temperature) we developed a capillary zone electrophoresis method permitting their measurements in the single run, without any derivatization procedures. The best separations were obtained within less than 30 min employing a 10 mmol/l phosphate buffer, pH 2.8, 18 °C, 15 kV voltage. Fairly good precision with a linear relationship between peak area and concentrations (r = 0.995–0.999) were obtained. The method was used to analyze human capillary blood.