Field sampling technique for the ‘fast reactive’ aluminium fraction in waters using a flow injection mini-column system with inductively coupled plasma atomic emission spectrometric and inductively coupled plasma mass spectrometric detection

Abstract

A novel field sampling strategy for the ‘fast reactive’ Al fraction in natural waters is described. The method is based on the isolation of the Al fraction which reacts with 8-hydroxyquinoline in under 3 s at pH 5.0. The resulting Al–8-hydroxyquinoline complex is sorbent-extracted from the sample stream onto mini-columns containing Amberlite XAD-2 non-ionic resin. The retained ‘fast reactive’ Al is then eluted with 1.0 mol l^–1 HCl for on-line element-specific detection by inductively coupled plasma atomic emission spectrometry or inductively coupled plasma mass spectrometry (ICP-MS). Data from field sampling trials show good agreement with those for the toxic Al fraction as measured by an established high-performance liquid chromatography technique. Between-column relative standard deviations of 8% at the 100 µg l^–1 level, a limit of detection of 1.8 µg l^–1(ICP-MS) and ease of use are the main advantages of the proposed method. The mini-column technique has the potential for solving many of the sample storage problems associated with Al-speciation studies, particularly for the determination of the more toxic (or ‘fast reactive’) fraction.