Fluorimetric determination of dissolved aluminium in natural waters after liquid-liquid extraction into n-hexanol

A sensitive and selective extraction-fluorimetric method for the determination of trace amount of dissolved aluminium in natural waters is developed in this study. Aluminium-lumogallion complex (Al-LMG) is extracted into n-hexanol, and the fluorescence can be enhanced substantially up to 20- fold. Compared to other publications in the literature, the method reported here is free from matrix effects, and the interference from iron and fluoride has been minimised successfully by Be²⁺ and o-phenanthroline, respectively. The detection limit of dissolved Al is 0.25 nM, which is one order of magnitude lower than the traditional fluorescence techniques, with a precision of 5% at an Al level of 40 nM and 6.7% at an Al level of 1.0 nM in routine analyses. The inter-calibration with electro-thermal atomic absorption spectrometry (ETAAS) technique for a variety of natural water samples shows a difference of 5-10%. The analysis of international SRM 1643C reference material by the method developed here provides a result consistent with the certified value. The successful inter-laboratory calibration practice demonstrates again the merit of present analytical procedure for the determination of Al in environmental and marine sciences.