Capillary electrophoresis separation and sensitive electrochemiluminescence determination of β-blockers and study on interaction between human serum albumin and the drug

A new CE with electrochemiluminescence detection using polyvinylpyrolidone as additive was developed for the simultaneous separation and determination of atenolol, esmolol, and bisoprolol. A simple and direct field-amplified sample stacking method was integrated to enhance the detection sensitivity of this method. By injection of a short plug of water before sample introduction, the sensitivity of atenolol, esmolol and bisoprolol can be easily improved 38, 26, and 37-fold, and LODs reach 3.4 x 10(-9), 3.5 x 10(-9), and 2.2 x 10(-9) mol L-1, respectively. The precision (%) of the peak area and migration times were in the range of 2.2 to 3.7 and 0.4 to 0.8 within a day and 3.1 to 5.5 and 3.9 to 4.5 in three days. The LOQ (S/N = 10) of three beta-blockers are 7.7 x 10(-8), 8.6 x 10(-8), and 6.7 x 10(-8) mol L-1 in human urine, and 1.1 x 10(-7), 1.4 x 10(-7), and 9.1 x 10(-8) mol L-1 in human serum. The recoveries (%) of three analytes at different concentration levels in human urine and serum samples are between 86.2 and 103.7%. The proposed method was successfully applied to the determination of three analytes in human urine and human serum samples. The interaction between human serum albumin and esmolol was studied by this method and the number of binding sites and the binding constant of human serum albumin and esmolol were estimated to be 5.7 and 7.1 x 10(4) L mol(-1), respectively.