Automated continuous-flow hydride generation with inductively coupled plasma mass spectrometric detection for the determination of trace amounts of selenium(IV), and total antimony, arsenic and germanium in sea-water

An automated continuous-flow hydride generation system was developed for the determination of trace amounts of Se^IV and total Sb, As and Ge in sea-water using ICP-MS detection. Since the same responses can be obtained between the Sb species Sb^V and Sb^III, among the As species As^V, As^III, monomethylarsonic acid and dimethylarsinic acid, and between the Ge species Ge^IV and monomethylgermanium, a single Sb, As and Ge species can be used for calibration. A sensitivity enhancement was observed when methanol was used for matrix modification. Matrix modification was also useful for achieving recoveries close to 100% in recovery tests performed on a sea-water sample. Detection limits of 2.2 ng l^-1 for Sb as Sb^III, 6.5 ng l^-1 for As as As^V, 2.4 ng l^-1 for Ge as Ge^IV and 0.5 ng l^-1 for Se^IV were obtained. For replicate determinations in both a standard solution and a real sea-water sample, the repeatabilities were within 7% (as RSD). The proposed method is rapid (15 samples can be analysed per hour) and sufficiently sensitive to allow trace amounts of Se^IV and total Sb, As and Ge to be directly determined in surface sea-water samples taken at a high latitude of the North Pacific Ocean from Japan to Canada.