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合成了新偶氮化合物1-(2-吡啶偶氮)-2-氨基萘(PAAN),并研究了它与钴的显色反应,在pH4.0～5.0的醋酸-醋酸钠缓冲溶液中,Co~(2+)与PAAN形成红色螯合物,λ_(max)=550nm.ε达1.0×10~5L·mol~(-1)·cm~(-1)(乙醇-水溶液)和5.16×10~4 L·mol~(-1)·cm~(-1)(OP-水溶液),钴与显色剂的组成比为1:2.钴量在0～11μg/25ml范围内遵守比耳定律.该显色反应选择性好.仅Ni~(3+).Fe~(3+).Cu~(2+).Pd~(2+)干扰,可通过加入盐酸酸化至1mol/L,破坏上述离子的配合物而消除,在不加任何掩剂的情况下.测定了土壤、茶叶和维生素B_(12)中的钴,结果满意.
The new azo compound 1- (2-pyridylazo) -2-aminonaphthalene (PAAN) was synthesized and its color reaction with Cobalt was studied. In the acetic acid-sodium acetate buffer solution with pH 4.0 ~ 5.0, Co 2+ formed a red chelate with PAAN, λ max = 550 nm, ε up to 1.0 × 10 5 L · mol -1 cm -1 (ethanol-water solution) and 5.16 × 10 ~ 4 L · mol -1 (cm -1) (OP-water solution), the composition ratio of cobalt to color reagent is 1: 2. The cobalt content is in the range of 0 ~ 11μg / 25ml (3 +). Fe ~ (3 +). Cu ~ (2 +). Pd ~ (2+) interference can be acidified to 1mol / L by adding hydrochloric acid, The destruction of the above ions and the elimination of complexes, without any mask in the case of determination of the soil, tea and vitamin B_ (12) of cobalt, with satisfactory results.