本文报道在非离子表面活性剂Tween—80存在下,pH为4.0～7.0时,PAN与钴的显色反应,用光度法直接测定人发中钴含量的方法。1 主要试剂 1—(2—吡啶偶氮)—2—萘酚(PAN):0.1%(乙醇配制) NH_4OAc—HOAc缓冲溶液:pH 5.2 Tween-80:20%溶液钴标准溶液:1μg·ml~(-1)2 分析方法称取1.0000g发样于100ml烧杯中,加入混酸(HNO_3:HClO_4=5:1)15.Oml,盖上表面皿,于水浴上加热溶解,待硝化完全,白烟冒尽取下烧杯冷却后,加少量水溶解并转移至25ml量瓶中,然后加入草酸铵 This paper reports the color reaction of PAN with cobalt in the presence of nonionic surfactant Tween-80 at pH 4.0-7.0, and the direct determination of cobalt content in human hair by spectrophotometry. 1 Main reagent 1- (2-pyridylazo) -2-naphthol (PAN): 0.1% (ethanol preparation) NH_4OAc-HOAc buffer solution: pH 5.2 Tween-80: 20% solution Cobalt standard solution: (-1) 2 Analysis method Weigh 1.0000g hair sample in a 100ml beaker, add mixed acid (HNO_3: HClO_4 = 5: 1) 15. Oml, cover the watch glass, dissolved in a water bath heated to be completely nitrified, white smoke To remove the beaker cooling, add a small amount of water dissolved and transferred to a 25ml volumetric flask, and then add ammonium oxalate