Rapid determination of trace semicarbazide in flour products by high-performance liquid chromatography based on a nucleophilic substitution reaction.

Semicarbazide, a toxic food contaminant, widely exists in food products and it originates from the thermal degradation of a food additive of azodicarbonamide or a metabolite of nitrofurazone abused in meat specimens. Many previous methods for semicarbazide determination usually required expensive instruments, difficult-to-prepare monoclonal antibodies, and a long operation time. In this study, a high-performance liquid chromatography method was developed for the rapid determination of trace semicarbazide coupling with a nucleophilic substitution reaction firstly using 4-nitrobenzoyl chloride as derivatization reagent. The derivatization reaction was mild at room temperature for 1 min in neutral solution. Then, semicarbazide derivative was separated and quantified by high-performance liquid chromatography with ultraviolet detection under optimal separation conditions at λmax = 261 nm. The proposed method offered the detection limit of 1.8 µg/L and was successfully applied for the rapid determination of trace semicarbazide in flour products. Semicarbazide in positive real samples could be actually found and quantified in the range of 0.47-7.53 mg/kg. The recoveries were 76.6-119% with relative standard deviations of 0.5-9.1% (n = 3). This developed method was rapid, reliable, and convenient for the determination of trace semicarbazide in food.