Determination of Methyldibromoglutaronitrile (MDBGN) in Skin Care Products by Gaschromatography-Mass Spectrometry Employing an Enhanced Matrix Removal (EMR) Lipid Clean-Up

A new application of QuEChERS (Quick, Easy, Cheap, Efficient, Rugged, and Safe) extraction followed by enhanced matrix removal-lipid cleanup and GC-MS analysis is proposed for skin care products. The method is applied to determine methyldibromo glutaronitrile (MDBGN), a preservative frequently used in cosmetic products before being banned for its allergic reactions, so as to unmask its now-prohibited use. The new validated procedure consists in extracting the cosmetic products with acetonitrile, removing the lipid matrix and then water and solid particles from the organic mixture by two dispersive solid-phase extractions (dSPE) in sequence and, lastly, analyzing the extracts in GC–MS. Compared to classic liquid–liquid extraction with chloroform, the method has superior features in terms of applicability to cosmetics, ease of use, working times optimization and, above all, reduction of analytically interfering lipidic constituents. Practical Applications: The use of EMR-Lipid dSPE system followed by GC-MS analysis allows to trace and quantify a minimal amount of a banned preservative, MDBGN, in so-called “complex” matrices, such as cosmetic creams, managing them in a simple and efficient way. Therefore, this system can be proposed for further applications of extractive procedures, advantageously alternative to the classic liquid-liquid extractions, in the field of cosmetics analysis. The EMR-Lipid dSPE system shows the following advantages: much simpler use, as the system provides tubes already packaged with the clean-up phase, optimization of the working times, and noticeable reduction of extraction impurities allowing cleaner extracts to be obtained.