SPECIATION OF ARSENIC ANIMAL FEED ADDITIVES BY MICROBORE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

Phenylarsonic compounds have been used as poultry and swine feed addit ives for the purpose of growth promotion and disease prevention, Owing to the lack of suitable analytical methods, however, knowledge of the ir metabolism, environmental fate and impact remains incomplete, In or der to compensate for this, analytical procedures were developed that allow the speciation of arsenic animal feed additives by using microbo re high-performance liquid chromatography (mu HPLC) coupled on-line wi th ICP-MS, More specifically, reversed-phase (RP) chromatographic meth ods were optimised to achieve the separation of various phenylarsonic acids from each other and from the more toxic inorganic arsenic compou nds, This mode of chromatography, however, exhibits limitations, espec ially in the presence of naturally occurring organoarsenic compounds, The application of RP ion-pairing chromatography eliminates such short comings by minimising the co-elution of arsenic species, In general, t he mu HPLC-ICP-MS methods developed in this study provide high selecti vity, extremely good sensitivity, low limits of detection (low-ppb or sub-pg amounts of As), require small sample volumes (<1 mu l), minimis e waste and operate most efficiently under low mobile-phase flow rates (15-40 mu l min(-1)), which are compatible for use with other types o f mass spectrometers, e.g., electrospray, Reference materials containi ng naturally occurring arsenic compounds were spiked with phenylarsoni c compounds and then analysed by using the procedures developed in thi s study.