Sensitive and selective determination of aluminium by peroxyoxalate chemiluminescence detection of the lumogallion complex

For the first time, the feasibility of employing the reaction of bis(2,4,6-trichlorophenyl) oxalate with hydrogen peroxide, i.e. peroxyoxalate chemiluminescence (PO-CL) reaction, for the determination of Al via chemical excitation of the Al-lumogallion complex is demonstrated. Experimental factors that affect the CL signal, such as pH, solvent and buffer compositions, and CL reagent concentrations were investigated. When compared to the use of fluorescence (FL) for the detection of the Al-lumogallion complex or the use of PO-CL reaction for the detection of the Al-8-hydroxyquinoline complex, the use of PO-CL reaction for the detection of the Al-lumogallion complex was found to exhibit higher tolerance towards interferences from a variety of inorganic and organic matrix species. For example, in CL detection, the tolerance limits (defined as the concentration ratio of the matrix ion to Al giving rise to a change in the peak height of the CL or FL signal of the Al working solution by a magnitude of 3% as a certain amount of a matrix species is added) for Fe³⁺, Fe²⁺ and citrate ions using lumogallion as the chelating agent for the determination of Al were 25, 14 and 170, respectively, whereas in FL detection, the corresponding tolerance limits were 1, 0.1 and 2, respectively. Under optimized conditions, the limit of detection for Al was ca. 0.042 μg l^-1 (3σ) and the calibration plot from 0.582 to 533 μg l^-1 was linear (r = 0.999). The applicability of the present CL method was demonstrated for the sensitive and selective determination of trace Al present in natural water samples. The recoveries of Al were found to fall in the range between 90.4 and 109.7% and the average precision was 4.7%.