Determination of Aluminum in Natural Waters by Flow Injection Analysis with Spectrophotometric Detection

ABSTRACT A rapid flow injection analysis method is reported for the on-line determination of trace aluminum in natural water. The parameters for the formation of complex of aluminum with chrome azurol S were optimized in the presence of cetyltrimethylammonium bromide. Aluminum reacted with reagents to form the complex and was detected in a 30 mm flow cell with detection at 620 nm and a reference wavelength of 700 nm. The parameters were optimized based on a univariate experimental design. Potential interferences from concomitant ions were also evaluated. The method provided high sensitivity with a limit of detection of 20.1 nmol L−1. The linear dynamic range was from 50 to 5000 nmol L−1. The upper limit of the calibration curve was extended to 20 µmol L−1 using a less sensitive detection wavelength. The recoveries were between 97.4 and 103.4%, and the relative standard deviation was 0.64% (n = 8) for river water fortified with 200–1000 nmol L−1 aluminum. The sample throughput exceeded 50 h−1. The results from the flow injection method were in agreement with analysis by inductively coupled plasma mass spectrometry. The procedure was used to analyze aluminum in drinking water, rainwater, and Jiulong Jiang River water.