METHOD COMPARISON FOR THE DETERMINATION OF LABILE ALUMINUM SPECIES IN NATURAL-WATERS

An inter-laboratory comparison project to evaluate the portability of a standard method for the determination of aluminium species in waters and to investigate the probability of producing reference waters for aluminium speciation analysis is described. High-density polyethylene containers were found to be appropriate for the storage of water samples, intended for speciation analysis, after leaching with 10% (v/v) nitric acid for 48 h. A quality control programme for total aluminium in water samples was completed by all participating laboratories, showing the value of such a parallel programme, especially for aluminium with its inherent problems with contamination. Water samples (lake and tap) proved to be stable for up to 30 days, after which increasing pH caused aluminium hydroxy species to precipitate. A defined Driscoll-Pyrocatechol Violet fractionation method was found to be robust enough to be fully portable, the participating laboratories achieving relative standard deviations of 15% for the toxic ''labile monomeric'' aluminium fraction in the more stable water samples.