SPECIATION OF ARSENIC COMPOUNDS BY USING ION-PAIR CHROMATOGRAPHY WITHATOMIC SPECTROMETRY AND MASS-SPECTROMETRY DETECTION

Chromatography separation of arsenic compounds is important for chemic al speciation studies; yet a complete separation of several biological ly and environmentally important arsenic compounds has been difficult to achieve on a single column. We report here baseline resolution for arsenate, arsenite, monomethylarsonic acid, dimethylarsinic acid, arse nobetaine, arsenocholine, and tetramethylarsonium ion, by using mixed ion-pair reagents containing 10 mM hexanesulfonate and 1 mM tetraethyl ammonium hydroxide, as mobile phase. The complete separation of these anionic, cationic and neutral arsenic species on a reversed-phase C-18 column took only 12 min. Inductively coupled plasma mass spectrometry , hydride generation atomic absorption spectrometry and atomic fluores cence spectrometry systems were used for element-specific detection. T he speciation technique was successfully applied to studies of urinary excretion of arsenic compounds following one-time ingestion of shrimp . Arsenobetaine ingested from the consumption of shrimp was excreted i nto urine in its original form; and approximately 70% of the total ars enobetaine ingested was excreted into urine within 37 h after ingestio n.