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Objective To establish an infrared spectroscopic method for the rapid qualitative and quantitative analysis of caffeine and sodium benzoate in Annaka samples. Methods Qualitative and quantitative modeling samples were prepared by mixing high-purity caffeine and sodium benzoate. The characteristic absorption peaks of caffeine and sodium benzoate in Annaka samples were determined by analyzing the infrared spectra of the mixed samples. The quantitative model of infrared spectra was established by partial least squares （PLS）. Results By analyzing the infrared spectra of 17 mixed samples of caffeine and sodium benzoate （the purity of caffeine ranges from 10% to 80%）, the characteristic absorption peaks for caffeine were determined to be 1 698, 1 650, 1 237, 972, 743, and 609 cm-1 . The characteristic absorption peaks for sodium benzoate were 1 596, 1 548, 1 406, 845, 708 and 679 cm-1 . When the detection of all characteristic absorption peaks was the positive identification criteria, the positive detection rate of caffeine and sodium benzoate in 48 seized Annaka samples was 100%. The linear range of PLS quantitative model for caffeine was 10%-80%, the coefficient of determination （R2 ） was 99.9% , the root mean square error of cross validation （RMSECV） was 0.68% , and the root mean square error of prediction （RMSEP） was 0.91%; the linear range of PLS quantitative model for sodium benzoate was 20%-90% , the R2 was 99.9% , the RMSECV was 0.91% and the RMSEP was 1.11% . The results of paired sample t test showed that the differences between the results of high performance liquid chromatography method and infrared spectroscopy method had no statistical significance. The established infrared quantitative method was used to analyze 48 seized Annaka samples, the purity of caffeine was 27.6%-63.1%, and that of sodium benzoate was 36.9%-72.3%. Conclusion The rapid qualitative and quantitative analysis of caffeine and sodium benzoate in Annaka samples by infrared spectroscopy method could improve identification efficiency and reduce determination cost.

A new boronate affinity monolithic material was prepared and used as the extraction medium of stir cake sorptive extraction (SCSE). The porous boronate affinity sorbent was prepared by in situ copolymerization of 3-acrylamidophenylboronic acid (APB) and divinyl benzene (DVB). To achieve optimum extraction performance for benzoylurea pesticides, several parameters, including desorption solvent, pH value, ionic strength in sample matrix, extraction and desorption times, were investigated in detail. At the same time, a simple, sensitive and environment friendly method for the determination of benzoylurea pesticides in water and juice samples was developed by the combination of SCSE-APBDVB with HPLC equipped with a diode array detector. Under the optimized experimental conditions, the limits of detection (S/N = 3) for target analytes were 0.055-0.11 μg/L in water and 0.095-0.31 μg/L in juice. The precision of the proposed method was evaluated in terms of intra- and inter-assay repeatability calculated as RSD, and it was found that the RSDs were all below 9.0%. The developed method was successfully applied to the determination of benzoylurea pesticide residues in water and juice samples and satisfactory recoveries of spiked target compounds were in the range of 75.6%-109%. The results well demonstrate that the new sorbent can extract benzoylurea pesticides effectively through multi-interactions including boron-nitrogen coordination, hydrogen-bond and hydrophobic interactions between sorbent and analytes.

A simple, efficient and sensitive method for the simultaneous determination of nitrofurantoin (NFT), furazolidone (FZD) and nitrofurazone (NFZ) in feed and water samples was developed by stir bar sorptive extraction (SBSE) coupled to high performance liquid chromatography with diode array detection. The SBSE based on poly (vinylimidazole-divinylbenzene) (VIDB) monolithic material as coating was used to concentrate the three target analytes. To obtain the optimum extraction performance, several VIDB-SBSE parameters were investigated and studied, including pH value, ionic strength of sample matrix, extraction and desorption time. Under the optimized experimental conditions, the linear ranges were 0.5-200 microg/L for FZD, 0.25-200 microg/L for NFT and NFZ. The limits of detection (S/N = 3) were in the range of 0.068-0.11 microg/L for the three analytes. The precision of the proposed method was evaluated in terms of intra- and inter-day repeatability calculated as RSD, and it was found that the RSDs were all below 6%. The developed method was successfully applied to the determination of nitrofuran residues in animal feed and water samples. The satisfactory recoveries of the spiked target compounds were in the range of 80.6%-108%.