Field-amplified sample injection for the determination of albumin and transferrin in human urines by MEKC

An MEKC method combining field-amplified sample injection (FASI) has been developed for the analysis of albumin (Alb) and transferrin (TRF) in human urines. Various parameters affecting FASI preconcentration were optimized systematically. Under the optimum conditions, using electrokinetic sample injection for 90 s, the sensitivity was improved 77.6- and 45.3-fold for TRF and Alb, respectively, without loss of separation efficiency when compared with hydrodynamical sample injection for 5 s (0.5 psi). The detection limits of TRF and Alb were found to be 0.31 and 0.14 mg/L, respectively. The proposed method has been successfully applied to the determination of TRF and Alb in desalted urines from patients with kidney diseases, and the recoveries of TRF and Alb were 91.1-101.7%.