Photochemical vapor generation of iodine for detection by ICP-MS

Abstract

A systematic evaluation of UV-photochemical generation of volatile iodine species for detection by ICP-MS is described. Several UV-based systems were studied, the most advantageous design being a modified cyclonic spray chamber fitted with a 6 W mercury pen lamp supplying 1 ml min⁻¹ sample to a glass concentric nebulizer. Optimal conditions utilized a 5% v/v solution of acetic acid as the generation medium. The presence of the UV field enhanced signal intensity approximately 40-fold, providing a (blank limited) limit of detection of 0.7 pg ml⁻¹¹²⁷I⁺ and a precision of replicate measurement of 4% RSD at 10 ng ml⁻¹ iodine. Using DRC technology and O₂ as the reaction gas, suppression of ¹²⁹Xe⁺ provided an estimated LOD of 6 fg ml ⁻¹¹²⁹I⁺ in aqueous samples.