IMPROVED DETERMINATION OF ALUMINUM SPECIES IN WATERS USING FIA SEPARATION FLUOROMETRIC DETECTION TECHNIQUES

A Flow Injection fluorimetric detection system, based on the reaction between aluminum and 8-hydroxyquinoline-5-sulphonic acid (8-HQS) in a micellar medium (cetyltrimethylammonium bromide (CTAB)) has been incorporated into the Driscoll fractionation method for the speciation of aluminium in waters. Improved analytical performance over a standard batch Driscoll/Pyrocatechol Violet (PCV) method is demonstrated. Detection limits (0.9 mug l-1), speed of analysis (20 s), linear range (0-10,000 mug l-1), and sample volume (100 mul) are all superior to the batch PCV technique. A serious positive interference from Zinc, occurring in the 8-HQS method, has been overcome by the addition of 0.1% m/v 1, 10 phenanthroline to the post-column reagent. Good agreement between the conventional batch technique and our continuous flow determination for the important labile monomeric aluminium fraction in a series of waters has been demonstrated.