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 ²⁰⁷Pb and ¹²⁷I, 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.