Advanced Materials Research Vols. 1033-1034

Abstract: A kind of N-substituted maleimide - having two olefinic bonds with different reactivities, (S)-N-Maleoyl-L-leucine allyl ester ((S)-ALMI), was synthesized from maleic anhydride, L-leucine and allyl alcohol. Radical polymerizations were carried out to obtain optically active polymers using 2,2′-azobisisobutyronitrile. Structures of the monomer and polymers obtained were investigated by NMR measurements. In radical polymerizations, the solvents strongly affect the radical polymerization behaviors of (S)-ALMI.

Abstract: In this study, N,N-(2,4-diamino-1,3,5-triazinyl) diethylenetriamine were synthesized by cyanuric chloride, diethylenetriamine and ammonia with a novel process in three steps, and it can be used as charring agent in intumescent flame retardant. Its chemical structures were characterized by Fourier-transform infrared spectroscopy (FT-IR) and elemental analysis. Meanwhile, the TGA results showed that triazine-based charring agent had good thermostability. Furthermore, the fire performancce of composites blended by the flame retardant and polypropylene was investigated by vertical burning test. The results revealed good fire retardancy that flame retardant polypropylene with 5.1wt% charring agent, 2.8wt% anti-dripping and 20.1wt% APP, was reached UL-94 V-0 rating.

Abstract: In order to study the impact of moldy bran, drug koji and A.schutzenbachii fermentation vinegar on the aromatic substances in buckwheat vinegar, vinegars that adding moldy bran, drug koji and A.schutzenbachii were used to analyze the content of aromatic ingredients with GC-MS method. The results indicated that buckwheat vinegar by drug koji fermentation includes 29 kinds of aromatic substances, moldy bran fermentation buckwheat vinegar has 23 kinds of aromatic substances, A.schutzenbachii fermentation vinegar contains 20 kinds of aromatic substances.

Abstract: HPLC (High Performance Liquid Chromatography) method for danofloxacin(DAN), enrofloxacin(ENR), sarafloxacin(SAR) and difloxacin(DIF) residues in freshwater fish was developed. The fish sample was extracted with methanol-water-acetic acid(2/8/0.01, V/V/V), performed on a C18 solid-phase extraction column. With methanol+malonic acid-magnesium chloride aqueous solution as mobile phase, gradient elution at 30°C, inject volume was 20μL. The wavelength of UV detector was 280 nm. The linear rang of four drugs was 0.1~10μg/mL. In the level of 0.5μg/kg and 4.0μg/kg, the average recovery of the four kinds of drugs was 79.81%~92.03% , the RSD was 1.03%~4.07%. The limit of DAN, ENR, SAR, and DIF was 0.1μg/kg, 0.1μg/kg, 0.05μg/kg, and 0.05μg/kg individual. This method was employed to analyze freshwater fishes, such as catfish, chub and carp, because of its simplicity and high efficiency.

Abstract: Gentamicin is a kind of aminoglycoside antibiotics and widely used in the prevention and treatment of the duck diseases. A prediction model was established for the rapid detection of Gentamicin residue in duck meat using fluorescence analysis method according to the strong fluorescent characteristic of the generated derivative for Gentamicin and o-phthaldialdehyde (OPA) in the presence of emulsifier OP-10 and mercaptoethanol.The fluorescence spectra of the duck meat containing Gentamicin were analyzed, the optimum excitation wavelength of the material was 340 nm and the optimum emission wavelength was 442 nm. Fluorescence intensity and the concentration of the standard samples presented the good linear relationship, the linear correlation coefficient was 0.9963 and the limit of detection was 0.47 μg/mL in the dynamic rang of 0.5 ~6.5μg/mL. The correlation coefficient of regression equation was 0.9968 for the samples of duck meat extract. The experimental results showed that the fluorescence analysis method had a good performance and accuracy in detecting the Gentamicin residue in duck meat.

Abstract: A fast and effective method was developed for determination of Mn in leisure foods by incomplete digestion-microemulsion sampling-high resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS). Microemulsions were prepared with digestive liquor and n-butyl alcohol as an auxiliary emulsifier after incomplete digestion treatment. The factors influencing determination were investigated by single factor experimental design. The optimal determination conditions were found as follows: the tartaric acid (1 mg/mL) was added as a chemical modifier with the volume of 4 μL; pyrolysis temperature 1100°C; atomization temperature 2000°C. The results showed that the correlation coefficient was better than 0.996, the characteristic concentration was 0.09 μg/L, the precision (RSD) for 6 replicate measurements of Mn was 2.8% and the average of recoveries was 97.3%. F-test and t-test (95% confidence level) in between the proposed method and the microwave digestion-HR-CS GFAAS method had no significant difference. Therefore, the proposed method was accurate and stable with a high practical value. It provided scientific basis for determination of metal elements in food.

Abstract: A liquid chromatography-tandem mass Spectrometric method for the determination of diarrhetic shellfish poisoning including okadaic acid(OA) and dinophysistoxins-1(DTX-1) in mussel. After being extracted using methanol and water(80:20,V/V),The solution was defatted with n-hexane and extracted in chloroform. After being concentrated ,the residue was dissolved with n-hexane and acetone(20:80,V/V).Then the solution was cleaned-up by solid phase extraction(SPE) on an Si cartridge.The analytes were eluted with methanol - acetone(40:60,V/V). The quantitative and confirmatory determination of OA and DTX-1 were performed by MRM mode. OA and DTX-1 were determined in the negative ion mode. The calibration curves were linear. The method was accurate and reproducible, being successfully applied to the monitoring of OA and DTX-1.The recoveries of standard addition levels were 92.5%-96.7%. The relative standard deviations were all below 6.67%. The limit of quantitation (LOQ) for this method as defined by ten times signal to noise was 20μg/kg.

Abstract: Determination of β-carotene content in four types of leafy vegetables, water morning glory, kale, lettuce and Chinese cabbage by using a simple, rapid and low cost of UV-Visible method. This study was in the concentration range of 0.5 to 12 mg/L, and showed the linear regression equation y = 0.0764x - 0.0008, and an excellent linearity with correlation coefficient (R²) was 0.9999. The accuracy of the method analysis was reported by percentage recovery of about 80-106%. The precision was reported by percent of relative standard deviation and varies for intra-day 3.92% and inter-day 3.99%. The limits of detection and limit of quantification were 0.004 and 0.013 mg/L, respectively. Acetone is the most suitable for extraction, ratio of weight of samples to solvent, and extraction time was 1:3 g/mL and 10 min. Moreover, the most appropriate storage temperature for leafy vegetable samples is 4°C. Evaluation of β-carotene content under the suitable conditions in the kale, Chinese cabbage, lettuce and water morning glory was found to be 27.96 ± 2.99, 19.35 ± 1.92, 18.78 ± 0.88 and 18.48 ± 1.86 mg/100 g, respectively.

Abstract: The aim of this work was to develop a sensitive, simple and direct procedure for the determination of Cu, Cd, Cr, Pb, Mn and Al in the cooking wine by HR-CS GFAAS with a minimum sample pre-treatment. The analyses of the six metal elements were conducted using a high resolution continuum source atomic absorption spectrometer. The cooking wine as sample was just diluted in ultrapure water with 1.0% (v/v) HNO₃ and the analytical lines of the six metal elements were selected scientifically. The correlation coefficients better than 0.99 were obtained and the limits of detection were 0.86, 0.08, 0.28, 0.81, 0.61 and 1.54 μg/L for Cu, Cd, Cr, Pb, Mn and Al, respectively. Recoveries varied form 96.1% to 105.7%. The proposed method was applied to the determination of the six metal elements in the cooking wine and the results showed that the mass concentrations of Cu, Cd, Cr, Pb, Mn and Al were 2.10, 0.177, 7.98, 1.86, 22.3 and 217.2 μg/L, respectively. There was a good agreement between the proposed method and the microwave digestion-HR-CS GFAAS method, and F-test and t-test at 95% of confidence had no significant difference. Therefore, the proposed method was accurate and stable with a high practical value. It provided scientific basis for quality control in food industries.

Abstract: The effects of hot air drying temperatures (40-80°C) on apparent density, void fraction, shrinkage, total phenolics, total flavonoids and reducing power in germinated corn were investigated. The physical properties: apparent density, void fraction and shrinkage at moisture contents ranging from 13 to 35% dry-basis were determined using standard techniques. The result found that apparent density and the void fraction were linear in relation to the initial moisture contents. The apparent density increased from 44 to 50 kg/m³. The void fraction decreased from 78 to 58% with increasing moisture content. The chemical property resulted in 40°C hot air convection drying enhances total phenolics and total flavonoids to 6.41% and 50.00%, respectively, when compared with the control. Higher drying temperature resulted in lower total phenolic, total flavonoid content and reducing power of germinated sweet corn compared with the control.