A new method for the parallel determination of bound 2,3-epoxy-1-propanol (glycidol) and 2-and 3-chloropropanediol (2-and 3-MCPD) in oil matrices is presented. It is based on an improved alkaline catalysed release of MCPD and glycidol, followed by a transformation of glycidol to monobromopropanediol (MBPD), derivatisation with phenylboronic acid (PBA) and analysis by GC-MS. Quantification was performed using isotopic labelled standards. Method validation was carried out for the complete method procedure using glycidyl stearate and 3-chloropropanediol-1,2-bis-palmitoyl ester as reference compounds. Linearity was verified (r 2 >0.999) within the concentration range from 0.1 to 5.7 mg/kg. The limit of detection (LOD) for bound glycidol was 0.025 mg/kg in absence of 3-MCPD. Due to a lack of certified reference material a validation of bound 2-MCPD analysis was not feasible, but an indirect approach yielded a semi-quantitative estimation. The method was applied to the analysis of several different oils. None of the analytes was detected in virgin or crude oils. In contrast bound MCPD and bound glycidol was detected ubiquitously in refined oils. The determined concentrations of 3-MCPD and glycidol in the tested samples varied in 2 orders and 4 orders of magnitude, respectively. Bound 2-MCPD was estimated to occur commonly in refined oils. Practical application:The presented application is advantageous to other methods that are either not suitable for the parallel determination of bound glycidol and bound 2-and 3-MCPD within on step or are based on an estimation of bound glycidol contents by calculation. In comparison to those methods based on the direct determination of the single mother compounds this approach to convert the eventually unclear assembly of different MCPD-and glycidyl derivatives into the basic analytes glycidol and 2-and 3-MCPD simplifies identification and quantification, enhances the analytical sensitivity and lowers the risk of underestimation. Furthermore, the investigation of basic transformations that may occur during sample preparation can be helpful for a better understanding of the complex chemistry in MCPD and glycidol analysis. Results from analysis of different oils and fats can be used for an estimation of the occurrence and distribution of bound MCPD and bound glycidol.

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Esters of 2 - and 3-monochloropropane-1,2-diol (MCPD) and glycidol esters are important contaminants of processed edible oils used as foods or food ingredients. This review describes the occurrence and analysis of MCPD esters and glycidol esters in vegetable oils and some other foods. The focus is on the analytical methods based on both direct and indirect methods. Methods of analysis applied to oils and lipid extracts of foods have been based on transesterification to free MCPD and determination by gas chromatography-mass spectrometry (indirect methods) and by high-performance liquid chromatography-mass spectrometry (direct methods). The evolution and performance of the different methods is described and their advantages and disadvantages are discussed. The application of direct and indirect methods to the analysis of foods and to research studies is described. The metabolism and fate of MCPD esters and glycidol esters in biological systems and the methods used to study these in body tissues studies are described. A clear understanding of the chemistry of the methods is important when choosing those suitable for the desired application, and will contribute to the mitigation of these contaminants.

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A metal- and additive-free methodology for the highly selective, photocatalyzed C-H oxygenation of alkylarenes under air to the corresponding carbonyls is presented. The process is catalyzed by an imide-acridinium that...

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The food contaminants 3-chloro-1,2-propanediol (3-MCPD) and 3-MCPD fatty acid esters have attracted considerable attention in the past few years due to their toxic properties and their occurrence in numerous foods. Recently, significant amounts of the isomeric compounds 2-chloro-1,3-propanediol (2-MCPD) fatty acid esters have been detected in refined oils. Beside the interrogation which toxic effects might be related to the core compound 2-MCPD, the key question from the risk assessment perspective is again-as it was discussed for 3-MCPD fatty acid esters before-to which degree these esters are hydrolyzed in the gut, thereby releasing free 2-MCPD. Here, we show that free 2-MCPD but not 2-MCPD fatty acid esters were able to cross a monolayer of differentiated Caco-2 cells as an in vitro model for the human intestinal barrier. Instead, the esters were hydrolyzed by the cells, thereby releasing free 2-MCPD which was neither absorbed nor metabolized by the cells. Cytotoxicity assays revealed that free 2-MCPD as well as free 3-MCPD was not toxic to Caco-2 cells up to a level of 1 mM, whereas cellular viability was slightly decreased in the presence of a few 2-MCPD and 3-MCPD fatty acid esters at concentrations above 10 µM. The observed cytotoxic effects correlated well with the induction of caspase activity and might be attributed to the induction of apoptosis by free fatty acids which were released from the esters in the presence of Caco-2 cells.

In the present study, existing official methods for oils were modified in order to analyze free and bound MCPD and bound glycidol in fish. Free 3-MCPD was determined in aqueous extracts of fishery products. DGF standard methods C-VI-17(10) and C-VI-18(10) and the 3 in 1 method were modified and tested to quantify ester-bound 2-and 3-MCPD and glycidyl esters. The different methods were validated using spiked fish mince and a naturally contaminated reference material consisting of homogenized smoked sprat and fish sticks. The methods showed good agreement. Assay B of the modified DGF method C-VI-18(10) and the adapted 3 in 1 method allow a quantitative determination of bound 2-and 3-MCPD in fishery products. In addition, glycidyl esters can be quantified applying the 3 in 1 method. The screening of various fishery products showed that smoked fish may contain considerable amounts of free 3-MCPD. Concentrations ranged between 8 and 388 mg/kg wet weight (ww). Only traces of free 3-MCPD were found in all other fishery products. Fish sticks and fried fish products are potential sources of 3-and 2-MCPD esters, but large variation were observed. Bound 3-MCPD ranged between 45 and 377 mg/kg ww, bound 2-MCPD between 9 and 116 mg/kg ww. Practical applications:The European Food Safety Authority (EFSA) is calling for occurrence data of 2-MCPD, 3-MCPD, 2-MCPD ester, 3-MCPD ester, and glycidyl ester in foods including fishery products. At present, there is no official method for the determination of these food processing contaminants in fish and fishery products. Therefore, the approach of this study was to establish analytical methods for the quantification of free and bound MCPD and bound glycidol in fish, based on the modification of existing methods for edible oils. The adapted methods allow a sensitive quantitative determination of the target analytes in various fishery products.