Determination of cadmium in seawater by chelate vapor generation atomic fluorescence spectrometry

Highlights: • Cd can react with DDTC or DETP to form volatile species at room temperature. • Che-VG efficiencies were 85 ± 3% at 0.1 M HNO₃ and 90 ± 2% at 0.025 M HNO₃. • Cd in seawater can be determined with the oxide of APDC as a coprecipitator before analysis. A method for the determination of cadmium in seawater by chelate vapor generation (Che-VG) atomic fluorescence spectrometry is described. Several commercially available chelating agents, including ammonium pyrrolidine dithiocarbamate (APDC), sodium dimethyl dithiocarbamate (DMDTC), ammonium dibutyl dithiophosphate (DBDTP) and sodium O,O-diethyl dithiophosphate (DEDTP), are compared with sodium diethyldithiocarbamate (DDTC) for the Che-VG of cadmium, and results showed that DDTC and DEDTP had very good cadmium signal intensity. The effect of the conditions of Che-VG with DDTC on the intensity of cadmium signal was investigated. Under the optimal conditions, 85 ± 3% Che-VG efficiency is obtained for cadmium. The detection limit (3σ) obtained in the optimal conditions was 0.19 ng ml^{− 1}. The relative standard deviation (RSD, %) for ten replicate determinations at 2 ng ml^{− 1} Cd was 3.42%. The proposed method was successfully applied to the ultratrace determination of cadmium in seawater samples by the standard addition method.