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Photoinitiators are widely used to cure ink on packaging materials used in food applications such as carton boards and can contaminate the food by migrating into the food. In this contribution, a fast and reliable confirmation method for the determination of photoinitiators in dry foodstuffs is described: benzophenone (BP), 4,4'-bis(diethylamino) benzophenone (DEAB), 2-chloro-9H-thioxanthen-9-one (CTX), 1-chloro-4-ropoxy-9H-thioxanthen-9-one (CPTX), 2,2-dimethoxy-2-phenyl acetophenone (DMPA), 4-(dimethylamino) benzophenone (DMBP), 2-ethylanthraquinone (EA), 2-ethylhexyl-4-dimethylaminobenzoate (EDB), ethyl-4-dimethylaminobenzoate (EDMAB), 4-hydroxybenzophenone (4-HBP), 1-hydroxycyclohexyl phenyl ketone (HCPK), 2-hydroxy-4-methoxybenzophenone (HMBP), 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (HMMP), 2-isopropyl-9H-thioxanthen-9-one (ITX), 4-methylbenzophenone (MBP), 4,4'-bis(dimethylamino) benzophenone (MK) and 4-phenylbenzophenone (PBZ). Dry foodstuffs were extracted using acetonitrile, followed by the addition of inorganic salts to precipitate fatty residues. After filtration, the extract was analysed using ultra-performance liquid chromatography in combination with tandem mass spectrometry (UPLC-MS/MS). Quantification was carried out using benzophenone-d10 (BP-d10) as internal standard. The presented method was successfully validated in-house. Afterwards, the procedure was applied in a marketing study, investigating 97 dry foodstuffs purchased on the Belgian market. In 89% of the samples, at least one photoinitiator was detected. The photoinitiators BP, EDMA and DMPA were most frequently found, while some photoinitiators (CPTX, DEAB, DMBP, HCPK, HMBP and MK) were never detected. Copyright (C) 2016 John Wiley & Sons, Ltd.

A liquid chromatography tandem mass spectrometry (LC/MSn) method for the determination of 12 corticosteroids in bovine liver has been optimized and validated in accordance with the European Commission Decision 2002/657/EC. A bovine liver sample was deconjugated with B-glucuronidase/sulfatase enzyme, extracted with diethyl ether and further cleaned up with Solid Phase Extraction (SPE) before analysis with LC/MSn. Two different enzyme extracts (originating from Helix Pomatia and Keyhole Limpet) and three SPE elution solvents (ethyl acetate, acetonitrile and methanol) were compared during the optimization. Helix Pomatia is generally known as the enzyme most being used for enzymatic hydrolysis purposes. Nevertheless, when detecting corticosteroids in the low µg kg-1 concentration range, the Helix Pomatia extract may lead to interferences in the final LC/MSn chromatogram. When using the Keyhole Limpet enzyme extract, no interferences were observed and therefore, this extract was the best choice for enzymatic hydrolysis tested in this case. Ethyl acetate was used as elution solvent during the validation procedure since SPE elution with acetonitrile resulted in higher chromatographic backgrounds, while elution with methanol showed less reproducible results. Validation of the optimized method was carried out for 10 of the 12 corticosteroids, giving mean recoveries between 91 and 109%, and repeatability and reproducibility coefficients of respectively maximum 13.7 and 18.0%. The working ranges for the linear calibration curves were 5-20 µg kg-1 for prednisolone, methylprednisolone and prednisone and 0.5-4 µg kg-1 for the other compounds (coefficients of determination R² >= 0.97). Specificity, decision limit (CCA) and detection capability (CCB) were for all compounds within the EC specified limits.

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The European research project DIFFERENCE (“Dioxins in Food and Feed – Reference methods and New Certified Reference Materials”) was focussed on the development of an alternative methods for analysis of polychlorinated dibenzodioxins (PCDDs), dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs) using comprehensive multi-dimensional gas chromatography (GC×GC), gas chromatography combined with low resolution ion-trap mass spectrometry (GCLRMS/ MS), the CALUX bioassay and an Ah-PCR technique. GC combined with high resolution mass spectrometry (HRMS) was used as a reference method in all comparisons.

Het door de EU gefinancierde onderzoeksproject DIFFERENCE heeft geresulteerd in nieuwe technieken die de analysecapaciteit in Europa kunnen verhogen en kosten kunnen verlagen. Handig voor bedrijven die regelmatig voedingsmiddelen en grondstoffen analyseren. Bovendien is de methode geschikt om de dioxineachtige polychloorbifenylen (PCB’s) te meten die naar verwachting eind 2004 worden opgenomen in de EU-normen

The correlation coefficient is commonly used to evaluate the degree of linear association between two variables. However, it can be shown that a correlation coefficient very close to one might also be obtained for a clearly curved relationship. Other statistical tests, like the Lack-of-fit and Mandel's fitting test appear therefore more suitable for the validation of the linear calibration model. A number of cadmium calibration curves from atomic absorption spectroscopy were assessed for their linearity. All the investigated calibration curves were characterised by a high correlation coefficient (r > 0.997) and low quality coefficient (QC < 5%), but the straight-line model was systematically rejected at the 95% confidence level on the basis of the Lack-of-fit and Mandel's fitting tests. Furthermore, significantly different results were achieved between a linear (LRM) and a quadratic regression (QRM) model in forecasting values for mid-scale calibration standards. The results obtained with the QRM did not differ significantly from the theoretically expected value, while those obtained with the LRM were systematically biased. It was concluded that a straight-line model with a high correlation coefficient, but with a lack of fit, yields significantly less accurate results than its curvilinear alternative. ispartof: DTEW Research Report 0205 pages:1-10 status: published