Determination of Iron, Copper, Zinc, Lead, Nickel and Cadmium in Cosmetic Matrices by Flame Atomic Absorption Spectroscopy

Metals are commonly used in cosmetic products for blocking ultraviolet light or coloring pigments; however, some metals exceed specific concentrations and can cause serious safety issues such as skin troubles and allergies. It is, therefore, important to measure the exact amount of metal in cosmetic products. However, the exact concentrations of metals in cosmetics that contain many organic and inorganic materials like oils, polymers, waxes, polyols, surfactants, and metallic powders are difficult to analyze due to the matrix effect. In this study, we developed and optimized a method to characterize six different metals (Iron, Copper, Zinc, Lead, Nickel and Cadmium) in cosmetics by using Flame Atomic Absorption Spectroscopy (FAAS). Commercial products in liquid and powder phase were prepared for analysis and spiking solutions were added to the analyte. The method was developed by optimizing acid for decomposition, acid ratio, and sample weight. The recoveries for accuracy test ranged from 92–105% and the linearity correlation coefficients were no less than 0.99. The relative standard deviations (% RSD) for repeatability were between 0.5–2.0%. In addition, robustness and ruggedness test results showed consistent quality of data under different conditions. Consequently, the proposed method is a rapid and simple protocol to determine metals in liquid and powder type of cosmetics with a high confidence level.