Determination of cholesterol oxides by gas chromatography-flame ionization detection/mass selective detection and their occurence in lanolin-containing cosmetics and ointments.

OBJECTIVE: Cholesterol oxides (COPs) are thought to be of toxicological relevance in cholesterol-containing foods. For cholesterol-containing cosmetics and the like, no information is available up to this date. Therefore, the first of two main aims of this study was to develop and validate a method for determining COPs in lanolin-containing cosmetics such as lipsticks and fatty creams as well as in nipple ointments. The second aim was to study the occurrence of COPs and their concentration levels in the respective product classes. METHODS: The procedure is based on a published method for food comprising some necessary modifications. Sample preparation consisted of transesterfication, solid-phase extraction and silylation of target compounds. Separation of the derivatized COPs and their quantification were performed with gas chromatography (GC) using a flame ionization detector (FID) or a mass spectrometer (MS). RESULTS: The successful validation and the trouble-free application during the market survey showed that the method was fit for purpose. Total COP levels found were in the low per cent range (up to 3%) and surprisingly high, being many orders of magnitude higher than those published for foods. CONCLUSION: To our knowledge, we present for the first time a method for the determination of COPs in non-food consumer products. Furthermore, our study demonstrates that lanolin-containing cosmetics may be an additional exogenous source of COPs. We further show evidence, that at least part of the COPs are already formed on the sheep's wool.

Oxysterols in cosmetics-Determination by planar solid phase extraction and gas chromatography-mass spectrometry.

Sterol oxidation products (SOPs) are linked to several toxicological effects. Therefore, investigation of potential dietary uptake sources particularly food of animal origin has been a key issue for these compounds. For the simultaneous determination of oxysterols from cholesterol, phytosterols, dihydrolanosterol and lanosterol in complex cosmetic matrices, planar solid phase extraction (pSPE) was applied as clean-up tool. SOPs were first separated from more non-polar and polar matrix constituents by normal phase thin-layer chromatography and then focussed into one target zone. Zone extraction was performed with the TLC-MS interface, followed by gas chromatography-mass spectrometry analysis. pSPE showed to be effective for cleaning up cosmetic samples as sample extracts were free of interferences, and gas chromatographic columns did not show any signs of overloading. Recoveries were between 86 and 113% with relative standard deviations of below 10% (n=6). Results of our market survey in 2016 showed that some cosmetics with ingredients of plant origin contained phytosterol oxidation products (POPs) in the low ppm range and therefore in line with levels reported for food. In lanolin containing products, total SOPs levels (cholesterol oxidation products (COPs), lanosterol oxidation products (LOPs), dihydrolanosterol oxidation products (DOPs)) being in the low percent range exceeded reported levels for food by several orders of magnitudes.