A novel outlook on detecting microbial contamination in cosmetic products: analysis of biomarker volatile compounds by solid-phase microextraction gas chromatography-mass spectrometry

Cosmetic companies are required to control the optimal preservation of their commercial products, since microbial contamination in cosmetics represents an important risk for consumer health. Fast methods for cosmetic microbiological testing are of great industrial importance, facilitating the rapid release of products into the market. In this work, a novel approach based on microbial volatile organic compound (MVOC) analysis was proposed, for the first time, as an alternative method for the rapid detection of microbial contamination in cosmetics by SPME-GC/MS. Microbial volatiles from typical contaminants of cosmetic products were sampled above the headspace of standard cultures and from incubated samples. The volatile fraction analysis revealed, amongst other compounds, the presence of several odd-numbered carbon (C9–C15) methyl ketones and alkanols, which have been reported as characteristic compounds of bacterial origin. Some of them were found both in pure bacterial cultures and in the samples. However, other compounds not seen in cultures were seen in the cosmetics, suggesting that substrate is a very influential factor. These results also suggest that it could be clearly feasible to qualitatively identify viable microorganisms in cosmetics or even specific strains by detecting their volatile biomarkers, which would be a rewarding complement for other rapid methods. The results of the kinetic study performed on real samples further suggest the possibility of monitoring the contamination progress.