在中性条件下,蛋白质与邻苯三酚红-铜(Ⅱ)络合物相互作用,可使络合物颜色加深,该反应在20℃,反应10 min后达到平衡。邻苯三酚红与铜的摩尔比为5∶2时显色效果最佳。在最大吸收波长517nm处测量邻苯三酚红-铜(Ⅱ)络合物的△A,蛋白质的含量与△A呈良好线性关系。方法回收率为93.1%～108.5%,回归方程为δA=0.010c-0.025 5,相关系数0.990 3。采用该方法检验了多个批次牛奶样品中的蛋白质含量,结果令人满意。

In neutral medium,pyrogallol red-copper(Ⅱ) reacts with protein to form a complex.The color of solutions darkened obviously.At 20℃,the reaction reaches balance after 10min.The mole ratio of pyrogallol red and copper is 5∶ 2.At the largest absorb wavelength of 549nm,the darkening intensity is proportional to the concentration of protein.The recovery of the method is 93.1%~108.5%,the regression equation is δA=0.010C-0.0255 and R2=0.990 3.The inspection on many types of milk using this method leads to satisfying results.