IMPROVEMENT OF DETECTION SENSITIVITY OF ARSENIC SPECIES USING CAPILLARY ZONE ELECTROPHORESIS

Separation of four arsenic species (arsenite, arsenate, monomethylarso nic acid and dimethylarsinic acid) has been performed by Capillary Zon e Electrophoresis using an electroosmotic now modifier (dodecyltriethy lammonium dihydrogenphosphate, Q(12)) and UV detection at 190 nm. The best compromise between a good resolution of the peaks and the shortes t time of analysis has been found for the following values of the diff erent parameters considered: [Q(12)] = 10 mmol l(-1), V = -25 kV, pII 8, t = 30 degrees C. Under those conditions, detection limits are abou t 250 ng ml(-1) (in arsenic) for each species. Short-term and long-ter m repeatabilities have been demonstrated. Moreover, this method has be en successfully applied to an artificial solution mimicking a fish ext ract.