Detection of N-dimethylnitrosamine in dried aquatic products with QuEChERS low temperature extraction and GC-MS

  Objective  To establish a modified quick, easy, cheap, effective, rugged, safe (QuEChERS) method for rapid detection of N-dimethylnitrosamine (NDMA) in dried aquatic products with gas chromatography-mass spectrometry/selected ion monitoring (GC-MS/SIM) and low temperature extraction and purification.

  Methods  Five grams of sample was extracted with ethyl acetate (10 mL) and centrifuged under refrigeration; the extract was purified by octadecylsilane-bonded silica gel (C₁₈) and ethylenediamine-N-propylsilane (PSA) and separated using capillary column Rxi-624Sil MS (30 m × 0.25 mm × 1.4 μm). NDMA in the samples was detected with SIM and quantified by external standard method.

  Results  The calibration curve of NDMA was linear in the range of 1 – 200 μg/L, with a good correlation coefficient (r²) of 0.999 6, and the relative standard deviation (RSD) ranged 0.8 – 6.0%. The detection limit (3 S/N) was 0.50 μg/kg. The recovery of standard addition was between 88% – 102%. The NDMA was detected in fish and shrimp samples but not in shellfish samples collected in a aquatic product market in Zhanjiang city; the detected NDMA contents were 1.29 – 3.75 μg/kg for the fish samples and 0.50 – 2.63 μg/kg for the shrimp samples.

  Conclusion  The established method is simple, rapid, sensitive and effective, and is suitable for rapid screening and determination of N-dimethylnitrosamine content in dried aquatic products.