Ultra-trace determination of cadmium by vapour generation atomic fluorescence spectrometry

Abstract

The vapour generation of cadmium by reaction in aqueous solution with sodium tetraethylborate was performed using a conventional continuous flow reactor. This vapour generation system was successfully interfaced with atomic absorption and fluorescence instrumentation. A detection limit, with fluorescence detection, of 20 ng dm–3(3σn–1) was obtained after optimization of the chemistry using simplex routines. Interferences from transition metal ions (e.g., NiII, CuII) were observed but were attenuated by the use of citrate as a masking agent. Vapour generation atomic fluorescence spectrometry was successfully applied to the determination of cadmium in potable waters, a National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 1643c Trace Elements in H2O, and Community Bureau of Reference (BCR) Certified Reference Materials (CRMs) 144 Sewage Sludge–domestic and 145 Sewage Sludge–industrial. Full recovery of cadmium spikes was obtained from UK drinking waters. A value of 12.6 ± 0.5 ng cm–3 of cadmium was obtained for NIST SRM 1643c (certificate value = 12.2 ± 0.1 ng cm–3 of cadmium) whilst the cadmium content of BCR 144 and 145 (certificate value 3.41 ± 0.25 and 18.0 ± 1.2 µg g–1, respectively) was estimated at 3.34 ± 0.15 µg g–1(BCR 144) and 18.24 ± 0.7 µg g–1(BCR 145).