[Analysis of arsenic speciation in food condiments based on the online trapping/separation coupling system]

An online coupling system based on gas chromatography-hydride generation with atomic fluorescence spectrometry (GC-HG-AFS) for the analysis of arsenic species in food seasoning(soy sauce and vinegar) was developed. With absorbent cotton as separation medium, the volatile arsenic species released from the samples were cold trapped online by liquid nitrogen. Then, the baseline separation of the volatile arsenic species was achieved at the room temperature and the arsenic species were sensitively detected by atomic fluorescence spectrophotometer. The experimental conditions such as flow rates of carrier .gas (He), acid type and concentration, reducing reagent concentration and reaction time were discussed. Under the optimum conditions, the limit of detection for As(III), As(V), MMA(V) and DMA(V) was 0.2, 0.2, 0.3 and 0.8 ng x mL(-1), respectively. The recoveries of As(III), As(V), MMA(V) and DMA(V) in soy sauce and vinegar were 93.07%-103.54%. Compared with the traditional liquid chromatography separation algorithm, the method was rapid, sensitive without any complex sample pretreatment. It was suitable and practical for detection of arsenic especially inorganic arsenic in food seasoning.