Spectrophotometric determination of aluminium and nickel

A simple spectrophotometric method, based on the complexes with xylenol orange (XO) and EDTA, is presented for the rapid determination of aluminium and nickel, respectively, in synthetic samples of hydrotalcite. The method only requires the solubilization in sulphuric acid of the inorganic material before the ligand addition. Under optimum conditions, the complexes Al-XO and Ni-EDTA showed maximum absorption at 554 nm and 380 nm, respectively. The method obeyed Beer's law in the concentration range 0.14-1.8 microg mL(-1) of aluminium, and 30-2730 microg mL(-1) of nickel. Molar absorptivities were 2.45 x 10(4) and 14.85 L mol(-1) cm(-1) while Sandell's sensitivities were 1.1 x 10(-3) and 3.9 microg cm(-2) for aluminium and nickel, respectively. The standard addition technique was used and the recoveries obtained revealed that the proposed procedure shows good accuracy.