A Study on the Determination of Iodine in Serum, Fresh Milk, and Feed Additive by Methane Mixed Plasma/ICP/MS

Abstract

The total iodine is determined in serum, fresh milk and feed additive by ICP-MS. The addition of a small amount of methane into the coolant gas channel improved the ionization of iodine. The analytical sensitivity of the proposed Ar/CH4 system was superior to that of the conventional Ar one by several times. The preparation involves only a 25-fold dilution with a diluent by direct nebulization in plasma. The diluent composition is NH4OH (0.5% v/v) and the abundance of iodine is measured at m/z=127. In the present method, the detection limits obtained for iodine were 0.041 μg/L. The analytical reliability of the proposed method was evaluated by analyzing the certified standard reference materials (SRM). The relative error range of milk powder SRM in optimum condition is 2.30%-4.70%. The concentration ranges of iodine in the serum, fresh milk, feed additive were 12.4-40.2 μg/L, <0.01-3.11 mg/L, <10-8-2.60 g/Kg, respectively.