在ｐＨ４．３左右的Ｂｒｉｔｏｎ－Ｒｏｂｉｎｓｏｎ（Ｂ－Ｒ）缓冲溶液中，茜素红Ｓ（ＡＲＳ）与人血清白蛋白（ＨＳＡ）结合，生成红色的复合物，吸光度值与ＨＳＡ含量呈线性关系。复合物的吸收峰值λｍａｘ为５３０ｎｍ，比ＡＲＳ试剂本身红移１１０ｎｍ。其表观摩尔吸光系数ε＝１．０×１０４Ｌ·ｍｏｌ－１·ｃｍ－１。ＨＳＡ标准曲线在其质量浓度１０～９００ｍｇ／Ｌ间呈线性关系，最低检出限为３ｍｇ／Ｌ。研究了该配合物用于蛋白质分光光度法测定的基本条件。应用该法测定了人血清样品，回收率在９６．９％～１０２．１％范围内。实验表明该反应选择性、重现性和对照性均好，操作简便，适用测定浓度范围宽 Alizarin red S (ARS) binds to human serum albumin (HSA) in a Briton-Robinson (B-R) buffer solution at pH 4.3 to produce a red complex with a linear relationship between absorbance and HSA content. The absorption peak λmax of the complex was 530 nm, redshifted 110 nm more than the ARS reagent itself. The apparent molar absorptivity ε = 1.0 × 104L · mol-1 · cm-1. HSA standard curve in its concentration of 10 ~ 900mg / L was a linear relationship between the minimum detection limit of 3mg / L. The basic conditions for the determination of protein by spectrophotometry were studied. Human serum samples were determined by this method and the recoveries ranged from 96.9% to 102.1%. Experiments show that the reaction selectivity, reproducibility and control are good, easy to operate, suitable for the determination of a wide range of concentrations