Spectrophotometric Quantification of Toxicologically Relevant Concentrations of Chromium(VI) in Cosmetic Pigments and Eyeshadow Using Synthetic Lachrymal Fluid Extraction
Chromium(VI) salts are possible contaminants of the chromium(III) pigments used as colorants in eyeshadow preparations. The use of products containing these contaminants poses acute risks for sensitization and contact allergies. Chromium(VI) compounds are also classified as carcinogenic to humans (IARC group 1). An analytical method to analyse trace levels of chromium(VI) in eyeshadow was developed in this study. The method is based on an extraction of the chromium(VI) from the sample using a maximum extraction with alkali and additionally with synthetic lachrymal fluid to simulate physiological conditions. Following derivatization with 1,5-diphenylcarbazide, the extracted chromium(VI) is then quantified by spectrophotometry (540？nm). Validation tests indicated a method standard deviation (inter- and intraday) of 8.7% and a linear range up to 25？mg/kg. The average recovery was 107.9%, and the detection limit was 2.7？mg/kg. The applicability of the procedure was confirmed by the analysis of pigments and authentic eyeshadow matrices. 1. Introduction Eyeshadow preparations can consist of dispersions of the necessary pigments in emulsions, oil, or molten wax. Another possibility is to process the pigments and other ingredients in the form of a pressed powder. The pigment concentration can vary in a wide range between 5 and 70% [1]. According to the EU Cosmetics Directive 76/768/EEC (Annex IV), the only allowable green colorants are chromium hydroxide green and chromium oxide green . However, these chromium(III) pigments can be contaminated with chromium(VI), which may cause an allergic contact dermatitis [2]. Because of its allergenic character, the presence of chromium(VI) is prohibited in cosmetics by a German cosmetics regulation and also by the corresponding EU Directive 76/768/EWG. Contact allergies caused by chromium(VI) are generally known from reactions to chromium(VI) in cement or leather. Chromium(VI) can also be found in other consumer goods, particularly in green soaps and detergents [3]. However, only low levels of chromium(VI) are typically contained in cosmetics, and are not expected to lead to an initial sensitization. However, if a consumer has already been sensitized to chromium(VI) from other sources, the low concentrations in leave-on cosmetics could nevertheless be allergenic [4]. In this respect, the product that possesses the highest inherent risk is eyeshadow, because it may contain up to 70% of green chromium(III) pigments. The “Informationsverbund Dermatologischer Kliniken zur Erfassung und wissenschaftlichen Auswertung von
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