Online coupling of tandem liquid-phase extraction with HPLC-UV for the determination of trace N-nitrosamines in food products

N-Nitrosamines (NAs) are potent carcinogens and have been found in food products. Herein we report a simple tandem liquid-phase extraction (TLPE) method coupled with high-performance liquid chromatography (HPLC) for the determination of trace N-nitrosamines (NAs) in food products. The TLPE method is based upon the tandem implementation of pressurized hot water extraction (PHWE) and dispersive liquid–liquid microextraction (DLLME). The target analytes were first extracted with pressurized hot water, and then concentrated into an organic phase (n-octanol) in the DLLME procedure. The TLPE-HPLC system allowed the analytes to be extracted, concentrated and analyzed in a single step with minimal manipulation of the sample preparation, with an overall analysis time of 25 min. The optimized method showed good linearity (r2 ≥ 0.981) and satisfactory recoveries (74–117%) with good repeatability of the extractions (RSDs below 12.8%, n = 5). The limits of detection (LODs) for all nitrosamines in salted duck eggs were in the range of 0.08–0.55 μg kg−1.