Flow-injection and liquid chromatographic determination of aluminum based on its fluorimetric reaction with 8-hydroxyquinoline-5-sulphonic acid in a micellar medium

Aluminum reacts with 8-hydroxyquinoline-5-sulphonic acids (HQS) in cationic micelles of cetyltrimethylammonium bromide (CTAB) to form a strongly fluorescent compound. In the micellar media the formation of the Al—HQS complex is very fast, allowing a useful continuousdetermination of aluminum in flow systems. At pH 6.3, for 2 × 10^-4 M HQS and 2 × 10^-3 M CTAB the detection limit for a luminum by flow injection is 0.1 ng ml^-1. The calibration is linear up to 100 ng ml^-1 and the peak-height precision is 2% at the 10 ng ml^-1 level. Interfences are greatly decreased compared with the batch method. The reaction has also been applied to the post-column detection by ion chromatography of aluminium in fresh and high-salinity wates and for speciation of aluminium in blodd serum after separation of serum proteins by ion-exchange liquid chromatography.