J. Cosmet. Sci., 59, 441–448 (September/October 2008)Simultaneous determination of heavy metals in cosmetic products

An extremely small amount of several heavy metals have been detected in cosmetic products as impurities, which can cause skin allergies through percutaneous adsorption on the skin. We present here a fast, accurate, and highly sensitive method for simultaneous determination of Pb²⁺, Fe²⁺, Cu²⁺, Ni²⁺, Zn²⁺, Co²⁺, Cd²⁺ and Mn²⁺ in coloring agents and cosmetic products, to be evaluated by ion chromatography. All of these metals are well separated through a bifunctional ion-exchange column (IonPac CS5A) and detected by post-column reaction and spectrophotometric detection. The calibration graphs are linear ( r ² > 0.999), in the range 0.1–1000 μg ml^-1. Detection limits for a 200-μl sample solution are at the μg L^-1 level, which is sufficient for judging whether the product is safe or not. The relative standard deviations (RSDs) of the retention time and the peak area are less than 0.21 and 1.24%, respectively. The recovery rates are 97–104%. The result shows that the proposed determination method is more sensitive, more accurate, and faster than current methods such as HPLC, ICP-MS and Flame-AAS. The new method was applied to analyse the amount of heavy metals contained in 22 cosmetic products and 11 coloring agents.