关键词: N-亚硝胺；腊肉；QuEChERS；气相色谱-质谱法

Abstract: A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) protocol coupled to gas chromatography-mass spectrometry (GC-MS) method for the determination of eight volatile N-nitrosamines in Chinese bacon was established and applied to evaluate the risk of dietary exposure to N-nitrosamines in commercial samples. The samples were extracted with acetonitrile in an ultrasonic bath, and after freezing treatment, the extract was purified using primary secondary amine (PSA) and condensed by nitrogen blowing in water bath to a trace volume. Then, the N-nitrosamines were separated on a polar capillary column, detected in the selected ion monitoring (SIM) mode and quantified by the external standard method. The results showed that the calibration curves exhibited good linearity for the eight volatile N-nitrosamines (R2 > 0.997) with matrix effects between 0.86 and 0.98. The limits of detection (LODs) and the limits of quantification (LOQs) ranged from 0.05 to 0.14 μg/kg and from 0.15 to 0.47 μg/kg, respectively. The average recoveries at three spiked levels (0.3, 1.0 and 3.0 μg/kg) were between 71.3% and 94.1% with relative standard deviations (n = 6) in the range of 0.4%–11.2%. Only one of the 12 representative samples sold on the market showed a N-nitrosodiethylamine (NDEA) content exceeding the national standard limit (3.06 μg/kg), while the rest were lower than the limits for individual and total volatile N-nitrosamine (3.0 and 10.0 μg/kg, respectively). This method showed the advantages of good purification effect, low cost, high sensitivity and good accuracy, and was suitable for the detection of the eight volatile N-nitrosamines in Chinese bacon. And the risk level of dietary exposure to N-nitrosamines in Chinese bacon was relatively low overall.

Key words: N-nitrosamine; Chinese bacon; quick, easy, cheap, effective, rugged and safe; gas chromatography-mass spectrometry