Single drop surface modified graphite furnace atomic absorption spectrometry for large volume injection: determination of cadmium

Abstract

The W-treated pyrolytic graphite (PG) furnace made it possible to enhance the precision (RSD < 2%), detection limit (2.5 ng l⁻¹) and sensitivity of Cd by a 100 µl injection with 5 µl of 2000 mg l⁻¹ of Pd modifier for 300 firings. The morphological change of sample deposited during the dry stage was observed in order to understand the high precision of atomic absorption of Cd within a W-treated PG furnace. It was found with the W-treated PG furnace that the sample deposited was constricted into the center area of the sample compartment of the furnace at any volume in the range 10–100 µl and was vaporized smoothly without formation of any bubble. A distribution with higher density of Cd in the center area after the dry stage was observed by the atomic absorption measurement of the small cores collected from the furnace inner wall. The high precision resulted in the distribution of Cd during the dry process of sample solution. The recoveries of 60 ng l⁻¹ Cd added to snow, river and tap water samples were 96.4–105%.