An improved sample preparation (extraction and cleanup) is presented that enables the quantification of low levels of acrylamide in difficult matrixes, including soluble chocolate powder, cocoa, coffee, and coffee surrogate. Final analysis is done by isotope-dilution liquid chromatography-electrospray ionization tandem mass spectrometry (LC-MS/MS) using d3-acrylamide as internal standard. Sample pretreatment essentially encompasses (a) protein precipitation with Carrez I and II solutions, (b) extraction of the analyte into ethyl acetate, and (c) solid-phase extraction on a Multimode cartridge. The stability of acrylamide in final extracts and in certain commercial foods and beverages is also reported. This approach provided good performance in terms of linearity, accuracy and precision. Full validation was conducted in soluble chocolate powder, achieving a decision limit (CCalpha) and detection capability (CCbeta) of 9.2 and 12.5 microg/kg, respectively. The method was extended to the analysis of acrylamide in various foodstuffs such as mashed potatoes, crisp bread, and butter biscuit and cookies. Furthermore, the accuracy of the method is demonstrated by the results obtained in three inter-laboratory proficiency tests.

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An analytical method is reported to determine trace amounts of furan in several different commercial foodstuffs that are subjected to thermal treatment. The SPME-GC-MS method is rapid and robust, and entails the following steps: addition of deuterated furan to the sample, sodium chloride-assisted extraction into the headspace, cryofocussing, and finally fibre desorption and GC-MS analysis. Furan is quantified by the use of an external calibration curve, achieving a decision limit (CC alpha) and detection capability (CC beta) of 17 pg and 43 pg, respectively, as absolute furan concentration in a 10 ml headspace vial. The method is applicable to a wide variety of foods, including fruits juices, baby foods in jars, canned foods, pet food, coffee and coffee substitutes. Typical amounts of furan found in selected foodstuffs range from about 1 microg kg(-1) (fruit juice) to 110 microg kg(-1) (baby food containing cooked vegetables). In-house validation data show good precision and accuracy of the method, with a typical repeatability of between 5 and 16% in different food matrices, and trueness determined in orange juice and coffee as 87 and 93%, respectively. Moreover, the measurement uncertainty has been evaluated for two matrices (fruit juice and coffee). Studies on short-term stability of furan in certain foods are also presented, and show that the furan content decreases in food while heating for preparation or reconstitution.

A method is described for the determination of residues of the illegal antibiotic chloramphenicol (CAP) in milk powders. The analyte is quantified by liquid chromatography coupled to electrospray ionisation tandem mass spectrometry (LC-ESI-MS-MS) operating in negative ion multiple reaction monitoring mode (MRM) after a liquid-liquid extraction followed by a clean-up step on solid phase extraction (SPE) cartridge. Because of the presence of two chlorine atoms in the CAP molecule, four specific transition reactions of CAP were monitored by MS-MS in selecting m/z 321 --> 257, 321 --> 152 (35Cl2) and m/z 323 --> 257, 323 --> 152 (37Cl35Cl). Two calibration curves were constructed by plotting the area ratio of m/z 321 --> 152 versus 326 --> 157 and m/z 321 --> 257 versus 326 --> 262 against their corresponding amount ratio. Indeed, even if m/z 321 --> 152 was found to give a higher MS-MS response (calibration curve used by default), an interfering chemical substance was sometimes observed for some milk extracts and not for the transition m/z 321 --> 257. The quantitation method was validated according to the European Union (EU) criteria for the analysis of veterinary drug residues at 0.1, 0.2 and 0.5 microg/kg concentration levels using d5-CAP as internal standard. The decision limit (CCalpha) and detection capability (CCbeta) of CAP in milk were calculated for m/z 321 --> 152 at 0.02 microg/kg and 0.03 microg/kg, respectively, and for m/z 321 --> 257 at 0.02 microg/kg and 0.04 microg/kg, respectively. At the lowest fortification level (i.e. 0.1 microg/kg), repeatability and within-laboratory reproducibility were calculated for m/z 321 --> 257 both at 0.02 microg/kg and for m/z 321 --> 152 at 0.03 and 0.05 microg/kg, respectively. Moreover, the measurement of uncertainty of the analytical method was calculated at the same spiking levels and falls within the precision values of the within-laboratory reproducibility. This method can be applied to several types of milk powders (e.g. full cream, skim) and can serve as a monitoring tool to avoid that unacceptable levels of residues of CAP enter the food chain.

It has recently been suggested that the analytical methods that have been developed to date for the determination of acrylamide (AA) may underestimate the concentration of AA in certain foods, because significantly higher results were obtained upon extraction of the food matrix under alkaline conditions. The present study employs food (potato, rye) and chemical model systems to better understand the tentative release of AA under high pH extraction conditions. The experimental design is based on the generation of AA in an environment containing an AA-isotopomer, and by comparing the ratio of AA, respectively the AA-isotopomer, after extraction at pHs 7 and 12. The results show that the additional AA released is not due to improved extractability of AA from the food matrix, and should therefore be regarded as an extraction artefact. Strongly alkaline conditions seem to induce net formation of AA from water-soluble precursors formed during thermolysis.