GC/CI-MS/MS method for the identification and quantification of volatile N-nitrosamines in meat products.

A sensitive and selective method was developed and validated for the determination of nine N-nitrosamines in meat products. The N-nitrosamines were extracted with NaOH/methanol, partitioned into dichloromethane on a ChemElut column and cleaned-up by solid-phase extraction. All samples were spiked with (2)H isotope-labelled N-nitrosamine internal standard prior to extraction. After purification on a Florisil mini-column, the extracts were analysed by gas chromatography-chemical ionisation tandem mass spectrometry (GC-CI/MS/MS) using ammonia as reagent gas. The presence of N-nitrosamines in samples was quantified by isotope dilution mass spectrometry. The method was validated for linearity and range, accuracy, precision and sensitivity. Recoveries were calculated at three levels of concentration (0.5, 1 and 10 µg/kg) spiked in raw pork meat. The values were found between 95% and 110% with relative standard deviation (RSD) values between 5% and 11%. The excellent selectivity and sensitivity allows quantification and identification of low levels of N-nitrosamines in meat products (limits of quantitation (LOQs) 0.3-0.4 µg/kg). Finally, the method was successfully used to analyse a sample of canned meat and nine different cured meat products produced in Italy. N-Nitroso-dimethylamine was detected in all examined products in the range 0.3-1.1 µg/kg.

Nicotine determination in mushrooms by LC-MS/MS with preliminary studies on the impact of drying on nicotine formation.

A problem concerning significant amounts of nicotine in dried wild mushrooms (mainly Boletus edulis from China) has been reported to the European Commission. As a consequence, the European Food Safety Authority (EFSA) proposed temporary maximum residue levels (MRLs) of 0.036 mg kg(-1) for fresh wild mushrooms and 1.17 mg kg(-1) for dried wild mushrooms (2.3 mg kg(-1) for dried ceps only). The EFSA also highlighted the necessity for a monitoring and testing programme to be launched by food business operators at the start of the 2009 harvest season. In the present study, a quick and sensitive analytical method for routine analysis of nicotine in fresh and dried mushrooms was developed and validated by a single-laboratory procedure. The method, which employs an LC-MS/MS system and (+/-)-nicotine-d(4) as internal standard, has a limit of quantification of 6 and 60 microg kg(-1) for fresh and dried product, respectively. Analyses of samples spiked with different levels of nicotine showed recoveries ranging from 107 to 122%, with relative standard deviations of 2.9-10.1% depending on the spiking level. The combined uncertainties, calculated at a low level for frozen (0.015 mg kg(-1)) and a high level for the dried (2 mg kg(-1)) matrix, were 13 and 10%, respectively. Application of the method to real samples of mushrooms purchased on the market or obtained from local producers showed nicotine levels ranging 0.01-0.04 and 0.1-4.5 mg kg(-1) in fresh/frozen and dried matrices, respectively. To establish reasons for the unexpectedly high levels of the nicotine in dried matrices, preliminary laboratory experiments involving drying mushrooms were performed under various conditions.

Search for a more adequate test to predict the long-term migration from the PVC gaskets of metal lids into oily foods in glass jars.

As shown previously, the conventional testing procedure for simulating long-term migration from the gaskets of metal closures into oily foods does not adequately reflect reality. It appears to be impossible to accelerate migration to the extent that the situation at the end of the shelf life of a product can be anticipated in a few days or weeks. Therefore, we investigated whether long-term migration could be extrapolated from migration rates determined for new lids. Jars were kept in the normal upright position. Since heat treatment may have a strong temporary impact, migration during the initial heating for pasteurization or sterilization and storage at ambient temperature were determined using different lids. Commercial products were recalled from sales points throughout Europe to determine the real migration over extended periods of time and for jars with differing histories. This migration was compared with data from the short-term testing to investigate whether an empirical relationship could be derived. The results show that the short-term test enables the comparison of lids and plasticizers in the initial phase of migration, but that long-term extrapolation presupposes more complex kinetic modeling. The results also demonstrate that the legal relevance of "official" testing methods should be reconsidered to avoid conflict when food contact materials comply with migration limits in the test but not in actual application.

Application of liquid chromatography with electrospray tandem mass spectrometry to the determination of a new generation of pesticides in processed fruits and vegetables.

This paper describes a method for the sensitive and selective determination of 24 new pesticide residues (azoxystrobin, trifloxystrobin, kresoxim-methyl, fenazaquin, indoxacarb, fenothiocarb, furathiocarb, benfuracarb, imidachloprid, dimethomorph, fenpyroximate, hexythiazox, tebufenpyrad, tebufenozide, difeconazole, fenbuconazole, flusilazole, paclobutrazol, tebuconazole, tetraconazole, bromuconazole, etofenprox, fenhexamid, pyridaben) in apple puree, concentrated lemon juice and tomato puree. A miniaturized extraction-partition procedure requiring small amounts of non-chlorinated solvents was used. The extracts are analyzed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS) without any further clean-up step. The pesticides are separated on a reversed-phase polar column using a gradient elution. Fifty-five simultaneous MS-MS transitions of precursor ions were monitored (two or three for each pesticide). Studies at fortification levels of 0.001-0.020 and 0.010-0.200 mg/kg gave mean recoveries ranging from 76 to 106% for all compounds, except for imidacloprid, with (R.S.D.s) < or = 15%. The excellent sensitivity and selectivity of LC-MS-MS method allowed quantitation and identification at low levels also in difficult matrices with a run time of 20 min. With the developed method almost 100 samples of commercial fruit products (nectars, juices, purees) were analyzed. None of samples contained residues higher than 0.010 mg/kg.

Determination of pyrethroid pesticide residues in processed fruits and vegetables by gas chromatography with electron capture and mass spectrometric detection.

A gas chromatographic method was developed for the simultaneous determination of 12 pyrethroids (tefluthrin, bifenthrin, fenpropathrin, cyhalothrin, permethrin, cyfluthrin, cypermethrin, alpha-cypermethrin, flucythrinate, fenvalerate, fluvalinate, and deltamethrin) in tomato puree, peach nectar, orange juice, and canned peas. A miniaturized extraction-partition procedure requiring small amounts of nonchlorinated solvents is used. Samples are extracted with acetone, partitioned with ethyl acetate-cyclohexane (50 + 50, v/v), and cleaned up on a Florisil cartridge. The final extract is analyzed by gas chromatography with both electron capture and mass spectrometric detection modes. Studies at fortification levels of 0.010-0.100 mg/kg gave mean recoveries ranging from 70.2 to 96.0% and coefficients of variation between 4.0 and 13.9% for all compounds. Quantitation limits were < 0.010 mg/kg for electron capture detection.