应用吡啶偶氮类显色剂测定痕量汞,虽然已有报道但不多。本文研究了用2-[(3,5-二氯-2-吡啶)偶氨]-5-二乙氨基酚(简称3,5-diCl-PADAP)测定汞的适宜条件。试验表明,在OP存在及pH9.3的条件下,汞与显色剂形成1:2的紫红色配合物。配合物的最大吸收波长为570nm,表观摩尔吸光系数为1.06×10~5,汞浓度在0～25μg/25ml范围内遵守比尔定律。采用巯基棉分离,可有效地提高方法的选择性。所拟方法简单,快速,灵敏度高,选择 Determination of trace mercury using pyridine azo reagent, although not reported. In this paper, the suitable conditions for the determination of mercury with 2 - [(3,5-dichloro-2-pyridylazo) -5-diethylaminophenol (3,5-diCl-PADAP) Experiments show that, in the presence of OP and pH9.3, mercury forms a 1: 2 purple complex with the developer. The maximum absorption wavelength of the complex is 570nm, the apparent molar absorptivity is 1.06 × 10 ~ 5, Beer’s law is obeyed in the range of 0 ~ 25μg / 25ml. The use of mercapto cotton separation, can effectively improve the selectivity of the method. The proposed method is simple, fast, high sensitivity, choice