硫氰酸盐-吖啶红分光光度法在水相中测定痕量汞

Spectrophotometric Determination of Trace Mercury in Aqueous Solution with Thiocyanate-Acridine Red

在聚乙烯醇 阿拉伯树胶存在下 ,汞 (Ⅱ )与过量硫氰酸盐形成Hg(SCN) 2 -4 配阴离子 ,再与碱性阳离子染料吖啶红形成 1∶2的离子缔合物 ,当用试剂空白参比时 ,最大吸收波长在 5 83nm处 .表观摩尔吸光系数为ε583 =3.1× 10 5L·mol-1·cm-1,0～ 9μgHg(Ⅱ ) / 2 5mL范围内服从比尔定律 ,对 4μgHg(Ⅱ ) / 2 5mL测定的相对标准偏差为 2 1% (n =9) ,检测限 (3σ,n =11)为 0 .35 μg/L .加入适量混合掩蔽剂KF 磺基水杨酸钠 柠檬酸水溶液 ,即可消除干扰离子的影响 ,方法有较高的灵敏度和选择性 ,操作简便 ,可直接在水相中测定环境水样中痕量汞 (Ⅱ ) .

A highly sensitive spectrophotometric method for determination of mercury has been developed, based on mercury in an excess of thiocyanate to form Hg(SCN) 2- 4, then formation of the 1∶2 ion association complex of Hg(SCN) 2- 4 with acridine red in the presence of polyvinyl alcohol gum Arabic. The molar absorptivity is 3.1×10 5 L·mol -1 ·cm -1 . The maximum absorbance of ion association against the reagent blank is at 583 nm. Beer's law is obeyed in the range of 0～9 μg Hg(Ⅱ)/25 mL. The relative standard deviation for the determination of 4.0 μg Hg(Ⅱ)/25 mL is 2.1%( n =9), and the detection limit is 0.35 μg Hg(Ⅱ)/(3 σ,n =11). The procedure is relatively simple. Elimination of liminated the interference is achieved by adding the mixed masking agents of potassium fluoride sulphosalicylic acid citric acid into sample solution, so the determination has very good selectivity. Trace mercury in aqueous solution has been satisfactorily determined directly by the method.