Quality testing of human albumin by capillary electrophoresis using thermally cross-linked poly(vinyl pyrrolidone)-coated fused-silica capillary.

To detect the quality of medicinal human albumin by capillary electrophoresis, we produced a fused-silica capillary coated with thermally cross-linked poly(vinyl pyrrolidone) to prohibit protein adsorption. This type of capillary was easily obtained by injecting an aqueous poly(vinyl pyrrolidone) solution into a fused-silica capillary and thermally annealing it at 200°C. Notably, stable and low electro-osmotic flow was obtained in the poly(vinyl pyrrolidone)-coated capillary at pH 2.20-9.00, and the separation of a mixture of four basic proteins indicated that the poly(vinyl pyrrolidone)-coated capillary exhibits excellent repeatability and separation efficiency; moreover, the separation of these four basic proteins could even be achieved at pH 7.00. The protein recovery percentage of human serum albumin in a single-protein solution and a mixed blood proteins solution was determined to be 97.03 and 95.40% in the poly(vinyl pyrrolidone)50-3 (representing the concentration of the capillary-injected poly(vinyl pyrrolidone) aqueous solution, 50 mg/mL, and thermal annealing time, 3 h) capillary, respectively. Based on these results, we used the poly(vinyl pyrrolidone)50-3-coated capillary to quantify the protein content of human albumin, and the results obtained from run to run, day to day and capillary to capillary demonstrated that the coated capillary could be used for quality testing commercially available human albumin.