Simultaneous determination of N-nitrosamines in ready-to-cook dishes: optimized extraction-purification protocol and comparative quantification by GC-MS/MS versus GC-Q/TOF MS.

Ready-to-cook dishes have flooded into global markets, raising widespread food safety concerns. N-nitrosamines (NAs) are recognized carcinogens generated during food processing, yet few contamination surveys have been reported for NAs in ready-to-cook dishes. To address the analytical challenges posed by complex matrices of ready-to-cook dishes, a steam distillation-solid phase extraction pretreatment system was optimized (2 mL hexane for cleanup; 10 mL dichloromethane for elution) and coupled with gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) and gas chromatography quadrupole time-of-flight mass spectrometry (GC-Q/TOF MS). This study established a reliable method for detecting 11 types of NAs. The comparative evaluation of the two platforms was conducted and the validated method was applied to assess NAs contamination levels in 91 ready-to-cook dish samples. Both platforms exhibited good linearity (10-200 μg/L, r ≥ 0.999). Limits of detection (LODs) for GC-Q/TOF MS (0.002-0.89 μg/kg) were slightly lower than GC-MS/MS (0.02-1.08 μg/kg). Recoveries ranged from 80.7% to 119.7% with relative standard deviations <9.1% for both platforms. GC-Q/TOF MS showed superior anti-interference capability. N-nitrosodimethylamine (NDMA) and N-nitrosodiphenylamine (NDPHA) showed detection rates of 34.1% and 52.7%, with maximum concentrations in "Octopus tentacle slices" and "Fish soup," respectively. Taking into account the detection rates and the presence of high-concentration samples, the category of aquatic products requires urgent attention. Overall, this study provides a reliable method and important data for evaluating NAs contamination in ready-to-cook dishes, highlighting the need for future research on health risk assessment and production specification control.