ARSENIC SPECIATION IN MARINE ORGANISMS - FROM THE ANALYTICAL METHODOLOGY TO THE CONSTITUTION OF REFERENCE MATERIALS

An analytical procedure for total arsenic and arsenic species quantifi cation in marine organisms has been developed. Fresh materials are fre eze-dried and reduced to powders before analysis. Arsenic is determine d either by energy dispersive: X-ray fluorescence (EDXRF) directly or by inductively coupled plasma optical emission spectrometry (ICP/OES) after microwave digestion. Arsenic speciation is performed on the extr acted sample using liquid chromatography coupled to ICP/OES for arseno betaine and arsenocholine determination and to the hydride generation- quartz furnace atomic absorption spectrometric technique for arsenite, arsenate, monomethylarsonic and dimethylarsinic acids quantification. Special precautions are taken to avoid losses or contaminations as we ll as to prevent analytical errors during the quantification stage. Ot her methods are applied and the corresponding results compared for eac h step of the procedure. The method is finally validated by means of i ntercomparison studies within the Measurements and Testing Programme o f the European Community (formely BCR).