Square wave voltammetry enables fast quantification and evaluation of Bi3+ extraction from eyeshadow samples

In this study, a square wave anodic stripping voltammetric method was developed to quantify Bi3+ in eyeshadow samples. The best results were obtained in 1.0 mol L−1 NaOH as the supporting electrolyte and the limit of detection was 8 nmol L−1 (1.7 ppb). Different sample pretreatment procedures were evaluated and the results showed that a combination of concentrated HCl, 30% (v/v) H2O2 and ultrasound was the best procedure to quantitatively extract Bi3+ from eyeshadow samples. The voltammetry of immobilized particles using a carbon paste electrode (CPE) was a simple and fast way to evaluate the efficiency of Bi3+ extraction of each sample pretreatment studied. This technique also has great potential to contribute to the validation of new sample pretreatment procedures if it produces a solid residue which can be immobilized onto the CPE surface and the analyte is electroactive. Moreover, the voltammetry of immobilized particles can be used to screen cosmetic raw materials for the presence of heavy metals, which is important to protect consumers from the harmful effects of these metals. This study has also demonstrated that voltammetry has great and almost unexplored potential to contribute to the quality control of cosmetic products regarding their heavy metal contents.