在铜(Ⅱ)与镉试剂的显色反应体系(即在含一定量铜(Ⅱ)及50 g·L-1吐温-80溶液0.5 mL,pH 9.6硼砂-氢氧化钠缓冲溶液2.0 mL和0.5 mg·L-1镉试剂1.0 mL的混合溶液)中加入异丙醇4.0 mL,加水定容至25 mL,于反应20 min后在498 nm波长处测其吸光度。试验表明:加入异丙醇使铜(Ⅱ)与镉试剂所生成的络合物的吸光度增高约30%。此新反应体系的表观摩尔吸光率达1.23×105L·mol-1·cm-1,铜(Ⅱ)质量浓度在0.28 mg·L-1以内与相应吸光度呈线性关系。测得方法的检出限(3s/k)为6.7×10-3mg·L-1。应用此方法分析了两个水样,并以此为基体用标准加入法做回收试验,测得平均回收率为98.2%,测定值的相对标准偏差(n=7)小于1.5%。

In a total volume of 25 mL, 4.0 mL of iso-propanol were added to the color reaction mixture containing a definite amount of Cu(Ⅱ), 0.5 mL of 50 g·L-1 Tween-80 solution, 2.0 mL of pH 9.6 borax-NaOH buffer and 1.0 mL of 0.5 mg·L-1 Cadio-alcoholic solution, and the absorbance of the solution was measured at 498 nm after reacting for 20 min. It was shown that the value of absorbance of the complex formed by Cu(Ⅱ) with cadion was raised to an extent of ca. 30% due to the addition of iso-propanol. Apparent molar absorptivity of the reaction system found was 1.23×105L·mol-1·cm-1. Range of linearity of Cu(Ⅱ) was found to be within 0.28 mg·L-1. Detection limit (3s/k) found was 6.7×10-3mg·L-1. Recovery was tested by standrd addition method using water samples as matrixes, average recovery found was 98.2% with RSD′s (n=7) less than 1.5%.