High Performance Liquid Chromatography of Organic and Inorganic Anions Using a Micellary Mobile Phase

Synopsis

Ion pairing chromatography has been widely used for the chromatographic determination of ionizable solutes. To date, the most commonly used ion-pairing reagents are non-micelle forming, but there can be advantages in using the micelle forming reagents. For example, no method existed previously for the separation and determination of dithiocarbamate salts, widely used as fungicides. High-performance liquid chromatography using micellar hexadecyltrimethylammonium chloride as the mobile phase provides a versatile and efficient technique for the separation of iodate, nitrite, bromide, nitrate and iodide. The distribution and retention of the inorganic anions is governed by their partitioning between the micelles and the mobile phase, and between the conditioned stationary phase and the mobile phase. Dithiocarbamate salts of varying hydrophobicity can be separated using micellar hexadecyltrimethylammonium bromide. Chromatographic efficiency measurements obtained for the hydrophobic solutes (phenol and benzene) and the ionic dithiocarbamate salts show that efficiency remains high even with high concentrations of methanol as the mobile phase modifier, with acetonitrile as the modifier, the efficiency falls as the concentration increases.