Polarograhic adsorptive wave of protein hydrolysate in Pb²⁺ and sodium hydroxide solution and its application

AimTo propose a new simple and sensitive voltammetric method for determination of proteins. MethodsProtein with sulfhydryl or disulfide bond in 0.5 mol·L^-1 NaOH, 1.5×10^-4 mol·L^-1 Pb²⁺ and 0.02% tetrabutylammonium iodide was heated in boiling water for 5 minutes. The reactive product gave a well defined reductive adsorption wave at -0.66 V (vs SCE) by means of single-sweep polarography, and the height of derivative wave was proportional to the concentration of proteins. ResultsThe peak height was linearly proportional to bovine serum albumin (BSA) or human serum albumin (HSA) concentration in range of 7.5×10^-10-3.0×10^-7 mol·L^-1 (^R_BSA=0.999 5, and ^R_HSA=0.999 0). The detection limit of BSA or HSA was 3.0×10^-10 mol·L^-1. For lysozyme (Lyso), the concentration range was from 1.4×10^-8to 1.3×10^-6 mol·L^-1(^R_Lyso=0.999 7) and the detection limit was 7.0×10^-9 mol·L^-1.ConclusionThe method is simple, rapid, sensitive and applicable to the assay of diluted human serum albumin samples.