阻抑褪色光度法测定痕量汞

Determination of Trace Mercury by Inhibition Discoloring Spectrophotometry

提出一种测定痕量汞的新的光度法。该法基于Ｈｇ（Ⅱ）对Ｈ２Ｏ２与离子缔合物ＡｇＣｌ·ＰＶＡ·Ａｇ~＋·Ｆｉｎ~－褪色反应的抑制效应，该离子缔合物对应于聚乙烯醇存在下Ｆａｊａｎｓ（法扬斯）法的终点，线性回归方程△Ａ＝０．０２＋ ４．０×１０^（－３）Ｃ_（Ｈｇ（Ⅲ））（μｇ／Ｌ），相关系数ｒ＝０．９９９２，Ｈｇ（Ⅱ）浓度在４．０～２０．０μｇ／Ｌ范围内服从比耳定律，检出限０．０４μｇ／Ｌ。该法用于废水样中Ｈｇ（Ⅱ）的测定，结果与双硫腙法结果相符。

A new spectrophotometric method for the determination of trace mercury was proposed. It is based on the fact that Hg(Ⅱ) inhibits discoloration of the ion association complex (AgCl· Polyvinyl alcohol .Ag+. Fluorescein anion) corresponding the end point of Fajans method in the presence of Polyvinyl alcohol by H2O2. The linear regression equation is △A = 0.020 + 4.0 x 10-3 CHg(μg/L), r = 0.9992. The Beer's law is obeyed in the range of 4.0 - 20.0 μg/L with the detection limit of 0.04 μg/L. The method has been used for the determination of Hg(Ⅱ) in waste water samples, and the results are in agreement with those of the dithizone method.