Determination of Mineral Composition of Lipsticks by Inductively Coupled Plasma-Atomic Emission Spectroscopy

Abstract

An inductively coupled plasma atomic emission spectrometry (ICP-AES) method was developed for the simultaneous determination of major, minor and trace elements in lipsticks purchased from Valencia markets. A comparative study between microwave-assisted digestion with HNO₃/H₂O₂ and dry ashing with Mg(NO₃)₂/MgO, as ashing aid, was performed in order to provide the highest sensitivity and to maximize the number of the analytes to be quantified. Microwave assisted digestion can be considered better than dry ashing method for avoiding Ba losses and providing data regarding Mg contents. Limit of detection values, equal or lower than few mg g^-1, were obtained for all the elements under study. To assure the accuracy of the whole procedure, the recovery of the proposed microwave assisted digestion method was evaluated using spiked samples at different concentration levels from 40 to 1600 mg L^-1. Quantitative average recovery values were obtained for all the elements evaluated, demonstrating the suitability of this methodology for the determination of mineral elements in lipstick samples. Finely, results obtained for the analysed samples were compared with those found in the literature to fuelling the lack of information about many elements existing in the lipsticks.