Abstract
Photoacoustic spectroscopy (PAS) has been applied to the determination of microamount of aluminum by measuring PAS intensity of aluminum oxinate after precipitation in the form of a mixture of aluminum oxine complex and naphthalene. The analytical procedure is as follows: take weakly acidic sample solution containing less than 20μg of aluminum in a 50-ml Erlenmeyer flask, add 1.0 ml of 1% oxine solution and 2.0 ml of acetate buffer (pH 5.2). Mix the solution well, and digest for a while, add rapidly with constant stirring 2.0 ml of 20% naphthalene solution in acetone. Filter under suction through filterpaper, wash with water, and dry in a vacuum desiccator for a few hours. Photoacoustic spectrum of the dried mixture is composed of peaks of aluminum oxinate at 395 nm and naphthalene at 320 nm. Determination of aluminum was performed by measuring the intensity ratio of the aluminum oxinate peak to the naphthalene signal. The calibration curve obtained by plotting the normalized intensity against the aluminum amount was linear in the range from 40ng to 20μg (sample solution: 20 ml). The method was successfully applied to the analysis of aluminum in the standard sample, Pepperbush (NIES SRM No. 1)
