ARSENIC SPECIES SEPARATION BY IELC-ICP OES - ARSENOCHOLINE BEHAVIOR

The separation conditions and quantification of As(III), As(V), monome thylarsenate (MMA), dimethylarsinate (DMA), arsenobetaine (AsBet) and arsenocholine (AsChol) are studied by Liquid Chromatography (LC) coupl ed directly to an Inductively Coupled Plasma Optical Emission Spectros copy (ICP/OES) system. The separation conditions are optimized to impr ove the resolution of the six arsenic species. Arsenocholine shows a p articular pattern of behaviour when phosphate is used as eluent: two p eaks are observed in the chromatogram, thus a systemic study assaying different pH and concentration of phosphate is carried out to improve resolution and analysis time when the six arsenic compounds are analyz ed in a mixture. Boric acid as mobile phase avoids the splitting of th e arsenocholine peak and leads to a good separation of the six arsenic compounds. Detection limits are stablished for the six arsenic specie s.