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.