Determination of chromium(III) and total chromium in seawater by on-line column preconcentration inductively coupled plasma mass spectrometry

An automated low-pressure flow injection method with on-line column preconcentration using inductively coupled plasma mass spectrometry is described for the determination of chromium(III) and total chromium in seawater. A home-made column of commercially available iminodiacetate resin, Muromac A-1, was used to concentrate chromium(III) in seawater at a pH of 3.0. Following washing of the column with water, the chromium(III) was eluted and transferred to the plasma with 0.70 M nitric acid. Total chromium was determined after the reduction of chromium(VI) to chromium(III) with a 2-mM hydroxylamine solution at pH 1.8. Detection limit (three times the relative standard deviation of the background) of chromium(III) in the artificial seawater based on eight replicate measurements was 0.020 ng ml−1 with a sample loading time of 120 s. The precision was ±1.9%. One sample can be processed in 5 min. Calibration was accomplished by means of artificial seawater. The proposed method was verified by the analysis of two Reference Standard Materials of seawater NASS-4 and CASS-3.