4-(2-吡啶偶氮)-间二苯酚光度法测定奶粉中的锌含量

Spectrophotometric Determination of Zinc in Milk with 4-(2-Pyridy Lazo)-Resorcinol

研究了显色剂4-(2-吡啶偶氮)-间二苯酚与锌的显色反应。在pH=9.0的硼砂-盐酸缓冲溶液中,非离子表面活性剂OP存在下,锌与4-(2-吡啶偶氮)-间二苯酚反应形成红色配合物,其最大吸收波长为500nm,表观摩尔吸光系数为6.24×104L·moL-1·cm-1。锌含量在0-60μg/50mL范围内符合比尔定律。该方法用于测定奶粉中的锌含量测定,加标回收率为97.8%-103.6%,相对标准偏差小于3.6%。

The colour reaction of Zn（Ⅱ）with 4-（2-pyridy lazo）-resorcinol（PAR） was studied. In the borax-hydrochloric acid buffer solution with the pH value of 9.0 and the presence of OP, zinc reacts with 4- （2-pyridy lazo）-resorcinol （PAR） to form a red complex. The apparent molar absorptivity was 6.24 ×10^4L ·mol^-1 .cm^-1at 500 nmwavelength. Beer＇s law is obeyed in the range of 0-60 μg/50mL for zinc （Ⅱ ）.The proposed method has been applied to the determination of zinc in milk with RSD less than 3.6% and the recoveries of 97.8%-103.6%.