Analysis of albumins, using albumin blue 580, by capillary electrophoresis and laser-induced fluorescence

We report a new method for analysis of albumins with albumin blue 580 (AB 580) by capillary electrophoresis (CE) using a relatively low-cost He-Ne laser. During separation, albumins and AB 580 formed complexes bearing intensive fluorescence in Trisborate (TB) buffers. The analysis of human serum albumin (HSA) was fast (4 min); reproducible (relative standard deviation (RSD) values of the migration time and peak height were less than 1% and 2%, respectively); and sensitive (the limit of detection at signal-to-noise ratio = 3 was 11 nM). Compared to other common dyes, such as bromphenol blue and merocyanine 540 for detecting albumins, AB 580 provides advantages of low fluorescence background, stability, sensitivity, and selectivity. Without sample pretreatment, this proposed method was employed to determine HSA in urine and blood cells from a normal male, with results of 5.2 ± 0.2 mg/L and about 8.2 ± 0.2 zmol/cell. To further increase the resolving power of this method, the tryptic digest of HSA was separated using 0.6% PEO. From the fact that only two peaks were shown in the electropherogram, we suggested that HSA and AB 580 formed 1:1 complexes. This method also allowed for rapid separation of HSA, deoxyribonuclease I, and their complexes.