次氯酸钠氧化碘-电感耦合等离子体质谱法同时测定地表水样品中的碘及铜、铅、锌、锰、铁的含量

取地表水样90.0mL置于100mL容量瓶中,用硝酸及氢氧化钠溶液调节其酸度至pH7~9之间,加水至96mL,加入0.6%(质量分数)次氯酸钠溶液1mL,放置2h使碘完全氧化至非挥发性碘酸盐,再加入硝酸3mL酸化使溶液总体积至100.0mL。这一处理实现了采用电感耦合等离子体质谱法同时测定碘与水样中铜、铅、锌、锰、铁的含量。在质谱分析中,测定207Pb和127I使用标准(STD)模式,其余元素均采用动能歧视(KED)模式。经试验,选用钬作为测定碘的内标。所测定6种元素的质量浓度在一定范围内与其相应的信号强度之间呈线性关系。另按规定方法对空白样品进行测定,计算得到6种元素的检出限(3s)依次为0.096,0.071,0.062,0.065,0.044,0.19μg·L^-1。以地表水实际样品为基体,各加入上述6种元素的标准溶液,按方法分析并进行回收试验,测得回收率在83.2%~116%之间。测定值的相对标准偏差(n=5)在2.4%~7.3%之间。同一样品经本方法和国家标准方法对所涉及的6种元素进行测定,两方法的结果基本一致。

ICP-MS Simultaneous Determination of Iodine and Copper,Lead,Zinc,Manganese and Iron in Surface Water Sample with Iodine Oxidized by Sodium Hypochlorite

90.0 mL of surface water sample was taken and its acidity was adjusted to pH 7-9. Water was added to make its volume to 96 mL, 1 mL of 0.6%(mass fraction) NaOCl solution was added and the solution was set aside for 2 h to have the iodine completely oxidized to iodate. 3 mL of HNO3 acid were then added to made its total volume to 100. 0 mL. By this treatment, iodine was transformed to the non-volatile state, and could be determined together with Cu, Pb, Zn, Mn and Fe in the same acidic sample solution by ICP-MS. In the MS analysis, STD mode was used for determination of 207 Pb and 1271, while KED mode was used for determination of the 4 remainder. Holmium was found to be a suitable internal standard for determination of iodine. Linear relationships between values of signal intensity and mass concentrations of the 6 elements were kept in definite ranges. Detection limits (3s) found by running blank determinations for 12 times. were given as follows: 0.096 (I), 0.071 (Cu), 0.062 (Pb), 0.065 (Zn), 0.044 (Mn), 0.19 (Fe)μg·L^-1. Tests for recovery were made by addition of standard solutions of the 6 elements to surface water samples as matrixes, results of recovery found were in the range of 83.2%-116%. Values of RSDs (n = 5) found were ranged from 2.4% to 7.3%. A same surface water sample was analysed simultaneously by the present method and the method given in the standards of HJ 778-2015 and GB/T 5750.6-2006. and the results obtained by these methods were in consistency.