Improved Determination of Aluminium Species in Waters Using FIA Separation/Fluorimetric Detection Techniques

Abstract

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 μg 1⁻¹), speed of analysis (20 s), linear range (0-10,000 μg 1⁻¹), and sample volume (100 μl) 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.

Key Words:

• Aluminium speciation
• 8-hydroxyquinoline-5-sulphonic acid
• micelles
• Driscoll/Pyrocatechol Violet
• water