Semi-on-line microwave-assisted digestion of shellfish tissue for the determination of selenium by electrothermal atomic absorption spectrometry

Abstract

An electrothermal atomic absorption spectrometric method for the determination of selenium in shellfish tissue at the microgram per gram level, following digestion of the sample in a continuous system including a microwave oven, is proposed. In the presence of palladium, the pyrolysis temperature for selenium can be raised to 1100 °C, and the signal is increased to a greater extent than with other reported chemical modifiers. The proposed method allows the determination of selenium in the range 25–250 µg l^–1(2.5–25 µg l^–1 Se after 10-fold dilution in the flow manifold). The precision achieved, expressed as the relative standard deviation, was 6.8% for within-run assays and 12.5% for between-run assays. The flow system is characterized by its simplicity (no special device is needed to process evolved gases during sample digestion). Samples can be introduced into the system as slurries made from unlyophilised fresh shellfish tissue (there is no difference between the mean results for unlyophilised and lyophilised samples.)