Study On The Analytical Methods Of Three Kinds Of Harmful Substances

For the determination of toxic substances in complex matrix, more effective sample pretreatment and sensitive determination techniques are necessary. In recent years, there is great progress on the modern analytical techniques. The establishment of faster, more accurate and applicable methods has been one of the hot topics in the field of analytical chemistry.In this paper, new chromatographic methods for the determination of three kinds of harmful substances in food and feed was investigated, mainly based on new pretreatment and detection techniques. The details were summarized as follows:In chapter2, a QuEChERS-HPLC method was established for the fast determination of13Phthalate esters in Chinese liquor. The targeted compounds were extracted by acetonitrile and purified by PSA (Primary secondary amine). The extracts were separated on a C18column with mobile phase composed of acetonitrile and water by gradient elution. The quantitation limits were0.14-0.91mg/kg. The recoveries were in the range from76%to132%and the relative standard deviations were under15%. The QuEChERS method is fast and simple which offers a quick determination for the phthalate esters in Chinese liquor.In chapter3, a simple and effective sample enrichment method of frozen zone melting liquid-liquid extraction was optimized and validated. The90mL beer was placed in container with lOmL dichloromethane. After agitation, the sample was kept in a freezer for16h at-19℃.The organic extract was analyzed by GC-FID. The average recovery was84.44%and the relative standard deviation was2.96%. As compared with conventional LLE, this technique offers numerous advantages, such as simplicity, low cost, ease of operation and a high enrichment factor.In chapter4, a HPLC method based on a new LED-induced fluorescence detector was developed for the fast determination of BaP in feed. Due to its high selectivity and sensitivity, the sample was extracted by acetonitrile and analyzed without any additional pretreatment. The linear range was over3orders of magnitude and the quantitation limit was0.83μg/kg. The average recovery was90.36%and the relative standard deviations were under10%. Compared with the other conventional analytical methods, the proposed method is easy and simple with a better sensitivity and lower detection limits.