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Baumgartner V.,State Laboratory of the Canton Basel City | Schwack W.,University of Hohenheim
Journal of Liquid Chromatography and Related Technologies

The HPTLC bioluminescence coupling is a method, which combines the separation ability of HPTLC with biodetection, applying the luminescent bacterium Vibrio fischeri that is also used in a cuvette assay for wastewater analysis according to a European norm method. As a result, a black and white image of the HPTLC plate is obtained, on which bioactive substances appear as dark spots on a brightly luminizing background. The evaluation of the image was usually done visually and, hence, qualitatively. Currently, available image evaluation programs showed to be unsuitable for quantitative evaluation because of insufficient background correction and/or tedious procedures. Furthermore, special corrections like a horizontal background correction and the recalculation of the sigmoid dose response relationship of the bacteria's reaction are needed. Available programs could not fulfill these requirements. Therefore, a method was developed by using existing common or freeware programs with which the proper corrections could be accomplished. Steps were the selection of the regions of interest from the HPTLC image, the conversion of the image file into a text file, followed by the main calculation in the spreadsheet program Microsoft Excel. For calculation, adapted versions of the cuvette test calculations were used. As Excel does not contain the necessary integration tools, two export methods were included. The first method allowed for a routine evaluation of chromatograms giving peak height and area as parameters. The second method enables an in-depth evaluation of chromatograms using an HPLC software leading to parameters like, e.g., signal-to-noise ratio, peak asymmetry, or peak width. Results obtained with the method were convincing. With a macro bundle, the calculations were not very time consuming and could be applied for routine use. Copyright © Taylor & Francis Group, LLC. Source

Schrack S.,State Laboratory of the Canton Basel City | Hohl C.,State Laboratory of the Canton Basel City | Schwack W.,University of Hohenheim | Niederer M.,State Laboratory of the Canton Basel City | Roux B.,State Laboratory of the Canton Basel City
International Journal of Cosmetic Science

Synopsis 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. Source

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