DETERMINATION OF ARSENIC COMPOUNDS IN EARTHWORMS

Earthworms and soil collected from six sites in Styria, Austria, were investigated for total arsenic concentrations by ICP-MS and for arseni c compounds by HPLC-ICP-MS. Total arsenic concentrations ranged from 3 .2 to 17.9 mg/ kg dry weight in the worms and from 5.0 to 79.7 mg/kg d ry weight in the soil samples. There was no strict correlation between the total arsenic concentrations in the worms and soil. Arsenic compo unds were extracted from soil and a freeze-dried earthworm sample with a methanol/water mixture (9.1, v/v). The extracts were evaporated to dryness, redissolved in water, and chromatographed on an anion- and a cation-exchange column. Arsenic compounds were identified by compariso n of the retention times with known standards. Only traces of arsenic acid could be extracted from the soil with the methanol/water (9.1, v/ v) mixture. The major arsenic compounds detected in the extracts of th e earthworms were arsenous acid and arsenic acid. Arsenobetaine was pr esent as a minor constituent, and traces of dimethylarsinic acid were also detected. Two dimethylarsinoylribosides were also identified in t he extracts by co-chromatography with standard compounds. This is the first report of the presence of dimethylarsinoylribosides in a terrest rial organism. Two other minor arsenic species were present in the ext ract, but their retention times did not match with the retention times of the available standards.