Development of a simple method for the determination of lead in lipstick using alkaline solubilization and graphite furnace atomic absorption spectrometry

A simple method was developed for determining the total lead content in lipstick samples by graphite furnace atomic absorption spectrometry (GFAAS) after treatment with tetramethylammonium hydroxide (TMAH). Multivariate optimization was used to establish the optimal conditions of sample preparation. The graphite furnace heating program was optimized through pyrolysis and atomization curves. An aliquot containing approximately 50 mg of the sample was mixed with TMAH and heated in a water bath at 60 °C for 60 min. Using Nb as the permanent modifier and Pd as the chemical modifier, the optimal temperatures were 900 °C and 1800 °C for pyrolysis and atomization, respectively. Under optimum conditions, the working range was from 1.73 to 50.0 μg L−1, with detection and quantification limits of 0.20 and 0.34 μg g−1, respectively. The precision was evaluated under conditions of repeatability and intermediate precision and showed standard deviations of 2.37%–4.61% and 4.93%–9.75%, respectively. The % recovery ranged from 96.2% to 109%, and no significant differences were found between the results obtained using the proposed method and the microwave decomposition method for real samples. Lead was detected in 21 tested lipstick samples; the lead content in these samples ranged from 0.27 to 4.54 μg g−1.