An automated method for monitoring aluminum in water samples based on a sequential injection platform

Abstract

The simple colour reaction between aluminum(III) and aluminon reagent was transferred to an automated sequential injection system. The experimental conditions were optimized in detail and found to be: sample pH, 4; zone sequence, aluminon–sample–HCl–aluminon; sample volume, 50 μL; volume of 1 M HCl, 5 μL; volume of reagent, 25 μL. The interference caused by iron was eliminated by the addition of thioglycolic acid. The calibration plot was linear over the range of 100–800 μg L⁻¹ Al(III) with limits of detection and quantitation of 13.0 and 43.3 μg L⁻¹, respectively. The sample throughput was 36 samples per hour. The RSD values for repeatability tested on 200 and 600 μg L⁻¹ Al(III) levels were found in the range of 1.97–2.36% and 1.69–2.57%, respectively. Nine real samples of well and pond water were examined and the results corresponded well with the commercially available colour test based on the chromazurol reaction. The recovery based on the standard addition method ranged from 100.00 to 103.41%. The developed method is intended to be applied for the quick screening of Al(III) content using a fully automated technique based on the sequential injection system.