Abstract Different analytical methods for the determination of chitosan content in water-soluble fertilizers by HPLC and spectrophotometry were established, and the hydrolysis conditions of chitosan were systematically studied. The results showed that the hydrolysis effect of 1+1 hydrochloric acid solution at 100℃ for 24h was the best. Linear range of HPLC with 1-phenyl-3-methyl-5-pyrazolone (PMP) as derivatizing agent. The detection limit and spiked recovery are 1~200 mg/l, 0.07 mg/l and 95~101% respectively, and the corresponding indicators of spectrophotometry are respectively 0~100μg, 0.47μg and 94%. Through comparison, the two methods have good consistency in the determination results of water-soluble fertilizer samples, and can meet the analysis requirements of chitosan content in water-soluble fertilizer. Among them, HPLC has fewer interference factors and higher efficiency. In addition, methyl fluorene chloroformate (Fmoc-Cl) was also used as a derivant to derive the hydrolysate of chitosan, and then detected by high performance liquid chromatography. It was found that the measured results were basically consistent with the above two methods, but the high performance liquid chromatography and spectrophotometry established in this study were not suitable for the determination of chitosan content in water-soluble fertilizer containing nitrate.

Abstract A method has been developed for the analysis of 16 polycyclic aromatic hydrocarbons(pahs) in shellfish sample. The sample was ultrasonically extracted, separated through Florisil and MIP-pahs column, enriched with vacuum steaming-nitrogen blowing, and determined by HPLC- VWD/FLD. The pre-treatment method was optimized. At the spiked level of 0.5, 1.5 and 2μg/kg, the average recoveries of 16 PAHs were 58.1%-89.6%, 60.6%-88.1% and 72.3%-98.0%; and the relative standard deviations(rsds) were 0.23%-11%, 1.3%-13%, and 1.5%-14%, respectively, in Mytilus coruscus. The detection limits of the method for 16 PAHs were 0.5μg/kg. This method was used for the analysis of 16 PAHs in Ostrea gigas Thunberg, Meretrix meretrix and Sinonovacula constricta.

Abstract Objective  To determine the quality of whole wheat products, it is necessary to establish a method for determination of alkylresorcinols(ars) which are the markers of whole wheat, black wheat and other cereal products. Methods  Taking wheat and black wheat as main research 2 o 2 bjects, factorial design was used to investigate the effect of extraction reagents(acetone, alcohol, and ethyl acetate), extraction methods(ultrasound for 30 min, 60 min, shaking at room temperature overnight), and sample status(granule, flour) on the determination of ars. And ars detection conditions was established by comparing chromatographic conditions and scanning fluorescence wavelengths. The ars content in some commercially available cereals were determined based on the methodological evaluation. Results Taking into account the toxicity of the reagents and efficiency, it was better that the comminuted sample was ultrasonically extracted with ethanol for 30 min before loading on the Waters CORTES-C18 column with ethanol: acetonitrile(30: 70, v: v). The fluorescence detector was set at a wavelength of 272 nm for excitation and 296 nm for emission to detect ars. The linear range was 0.050-10.0g/mL and the coefficient R 2 ≥0.9999. RSD of precision experiment was less than 5% and the spiked recovery rates of three levels were 94.5%-104%. The total amount of ars was 47.9-54.3 mg/100g in commercially available wheat and 53.6-60.9 mg/100g in black wheat. Conclusion  The liquid-fluorescence method established in this study can effectively and rapidly separate ars from wheat and black wheat and has the advantages of simple operation, high sensitivity and accuracy.

Abstract With the gradual advancement of knowledge and civilization, forensic science and technology is steadily developing and evolving. Chromatography, as an important analytical technique with the advantages of simplicity, rapidity and high sensitivity, has been widely used by researchers in various countries in the process of detecting toxic substances and drugs in forensic science. This paper presents a comprehensive analysis and exploration of chromatographic techniques from three perspectives: the development of chromatography, its classification according to the two-phase state, chromatographic separation mechanism and the nature of the stationary phase, and the applications of chromatographic techniques. The future development trend of chromatographic analysis technology is also prospected in order to provide new ideas for the development and research 2 o 2 f other technologies in thefield of forensic science.

Abstract The use of bisphenol-A (BPA) in global industry has been increasing in recent years, with emerging markets driving this growing demand. BPA applications in the food and beverage industry account for only 3 to 4% of global polycarbonate consumption, but its use is being re-examined as several scientific papers have come to light indicating a direct link between BPA and adverse health effects. Contamination of food and beverages occurs by migration of BPA from the containers that contain it (canned foods, wines, etc.), and is the main source of human exposure. To evaluate such exposure, an analytical method by gas chromatography coupled to mass spectrometry was developed and validated for the quantification of total BPA in urine of pregnant women attended at the Italian Hospital of Buenos Aires in 2013, with a limit of quantification of 2.0 ng/mL and a limit of detection of 0.8 ng/mL. Of the 149 urine samples analyzed, 66.4% were quantifiable, with the median total BPA of 4.8 ng/mL (4.3 ng/mg creatinine) and the geometric mean of 4.8 ng/mL (4.7 ng/mg creatinine).