ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY OF INORGANIC AND ORGANIC ARSENIC SPECIES USING CONVENTIONAL AND FAST FURNACE PROGRAMS

Analytical sensitivities for arsenate, monomethylarsonate, dimethylarsinate, arsenobetaine, arsenocholine and the tetramethylarsonium ion are determined by electrothermal atomic absorption spectrometry. Conventional and fast furnace programmes with and without a palladium-magnesium nitrate chemical modifier are studied. Special attention is paid to pre-atomization losses of the arsenic species tested. The conventional programme gives equal characteristic masses of about 16 pg of arsenic for all the species tested. The characteristic mass is defined as that mass of analyte which produces an integrated absorbance signal whose net area is equal to 0.0044 A s. The fast programme with the chemical modifier leads to slightly poorer sensitivities compared with the conventional programme. When using the fast programme without chemical modification, substantial preatomization losses, of the quaternary arsonium compounds in particular, are seen at a pre-treatment temperature of only 200-degrees-C.