Matrix Modification for Graphite Furnace Atomic Absorption Spectrophotometric Determination of Volatile Elements ( ). Determination of Trace Lead by Graphite Furnace Atomization

摘要

The graphite furnace atomic absorption spectrophotometric determination of trace lead in water samples was studied using matrix modifiers. In order to modify the sample matrix, the type and optimum amount of the modifier were investigated with a given concentration of Pb solution. In fact, if the matrix is not modified, lead has low ashing and atomization temperatures as to give a low absorbance with bad reproducibility because of its volatility. Therefore, optimum modifiers should be used to stabilize the atomization. In this work, the ashing and atomization temperatures were raised from 400 and 1,800?é to 1,000 and 2,000?é by the addition of palladium to 50 ng/mL lead solution as a modifier. The concentration of palladium was 5.0 ￥ìg/mL in the modified solution. Furthermore, if 1.5 ￥ìg/mL of aluminum was mixed with the palladium modifier as an auxiliary modifier, the ashing temperature could be increased 150?é additionally. With such a treatment, the sensitivity was improved more than 5 times of the solution unmodified and the reproducible results of less than 5% RSD were obtained in the samples of university's waste water and pipe-washing tap water. It could be concluded that this procedure was quantitative in the determination of trace lead from the recoveries of more than 88% obtained in the samples in which a given amount of lead was spiked.