Enhanced throughput with capillary electrophoresis via continuous-sequential sample injection

A significant fraction of the total analysis time (injection-to-injection) in capillary electrophoresis is dedicated to a rigorous between-run capillary rinsing/regeneration procedure, This is of particular importance with CE-based assays developed for high-throughput analysis of clinical samples. In this study, we examine the necessity of a between-run rinsing step when detergent is present in the separation buffer, Using three model analyte systems (hypoglycemic drug standards, urinary estrogen standards, fasted normal human urine), the reproducibility for migration time (MT), peak area (PA), and peak height (PH) with separation in a borate/phosphate buffer containing 75 mM sodium cholate was found to be acceptable in the absence of between-ran capillary cleansing, Continuous-sequential injection of hypoglycemic drug standards over the course of 39 consecutive runs without between-run capillary regeneration showed acceptable reproducibility. The average percent coefficient of variance values associated with MT(rel(MeOH)), PA, and PH over 39 consecutive runs were 2.22, 3.27, and 3.51%, respectively, In excess of 100 continuous-sequential injections could be performed in this manner without any significant effects on electroosmotic flow or reproducibility. Exclusivity of these results was ruled out with the continuous-sequential injection of the urinary estrogen and the human urine analyte systems under the same conditions, both of which yielded comparable results, The ability to circumvent or eliminate capillary rinsing procedures when detergent is a component of the separation buffer presents the possibility of decreasing the total analysis time (injection-to-injection) with certain analyte systems, the result of which will be to enhance sample throughput by 2-3-fold on single-capillary instrumentation.