Differential determination of trace amounts of iodide and iodate in water by solvent extraction-inductively coupled plasma atomic emission spectrometry

Abstract

Inductively coupled plasma-atomic emission spectrometry (ICP-AES) combined with solvent extraction has been investigated to determine trace amounts of iodide and iodate in water. Nonpolar solvents such as nonane and decane show higher signal-to-background ratios than the polar solvents such as xylene and diisobutyl ketone (DIBK). However, memory effects in the nebulizer spray chamber are severe. This phenomenon is discussed in relation to the characteristics of iodine such as the formation of the charge transfer complex and the solubility in the organic solvents.The detection limits at 178.28 and 206.16 nm for the original samples (concentration factor = 50) obtained by using xylene as the extradant are 8.3 and 21 ng ml −1 of I, respectively. By the back extraction of iodine from xylene into 0.5% ascorbic acid solution, the detection limit (concentration factor = 100) at 178.28 nm is improved to 1.6 ng ml −1. Most other ions except for the large amounts of bromide do not interfere. This method is applied to the analysis of brines and coastal seawaters.