Abstract

Direct determination of dissolved phosphate in sea-water by ion-exclusion chromatography in combination with inductively coupled plasma mass spectrometry is described. This method was developed as an independent, complementary approach to the standard colorimetric procedure used for the determination of dissolved phosphate in a proposed sea-water reference material. The developed on-line method is rapid, simple and accurate, requiring no sample pre-treatment. One determination can be completed in 6 min. The detection limit (3s), estimated at 0.06 µM (2.0 ng ml⁻¹ as P) with injection of only 100 µl of sea-water, is superior to the 0.15 µM achieved using colorimetry. The dissolved phosphate concentration in sea-water of 1.69 ± 0.04 µM measured by a standard additions technique using the proposed method is in good agreement with the 1.71 ± 0.04 µM determined using a classic colorimetric approach.