Advanced Materials Research Vols. 781-784

Abstract: A method was developed for simultaneous determination of imidacloprid,acetamiprid, thiabendazole and carbendazim in lentinus edodes, straw mushroom and oyster mushroom by HPLC. Acetonitrile was edded in the sample for extraction solvent, the sample was purified by NH₂ solid phase extraction cartridge,then detected by HPLC.The results showed that a good linearity in the range of 0.05~5.0μg/mL with the linear correlation coefficients of 0.9991~0.9997, the detection limits of imidacloprid, acetamiprid, thiabendazole and carbendazim were respectively 0.002 mg/kg,0.005mg/kg, 0.003 mg/kg and 0.003 mg/kg.Tests for recovery were made by addition of four pesticidess standards at three different concentration levels (0.1, 0.5 and 1.0 mg/kg) to the blank sample.The mean recovery rates were 86.0%~105.0% , the relative standard deviations were less than 3.5%.The sensitivity, accuracy and precision of this method were able to meet the requirements for pesticide residue analysis.

Abstract: In this paper, an easy, economical and effective nonaqueous micellar electrokinetic capillary chromatography (NAMECC) method for the simultaneous determination of two bioactive components (evodiamine and rutaecarpine) in Evodiae Fructus and its pharmaceutical preparations was developed for the first time. After optimization of the separation conditions and concentration conditions, the two alkaloids can be separated by using a fused-silica capillary column (57 × 75 μm I.D.) with a running buffer of 140 mM sodium cholate (SC) in methanol and detected with a diode-array detector (228nm). The second-order derivative electropherograms were applied for resolving overlapping peaks in complicated preparations. Regression equations revealed good linear relationships (correlation coefficients 0.9969-0.9999) between peak heights in second-order derivative electropherograms and concentrations of the two analytes. The relative standard deviations (RSD) of the migration times and the peak height of the two constituents were less than 0.49% and 1.6%. The recoveries of two constituents ranged from 93.5 to 105.6%. The results indicated that baseline separation of the analytes was hard to be achieved in real samples sometimes and second-order derivative electropherograms was applicable for the resolving and analysis of overlapping peaks.

Abstract: In this paper, graphene was used as the adsorbent for peptide enrichment, and followed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis. To study the adsorptive property of graphene, peptide angiotensin II was chosen as the model target. The enrichment material was analyzed by MALDI-TOF MS directly without desorption step. As a result, graphene showed good adsorptive capacity for peptide. After enrichment, the peak intensity and the signal-to-noise ratio were obviously increased.

Abstract: A novel method for the indirect determination of methimazole by discoloration spectrophotometry using Fe (Ш)-tiron system has been established.The various effect factors on the determination of methimazole by discoloration spectrophotometry using tiron-Fe (Ш) system were investigated in detail. The results showed that by controlling pH=2.8,Fe (Ш) could be reduced to Fe (II) by hydrosulfuryl (-SH) in methimazole molecule,and then using tiron as chromogenic reagent of Fe (Ш),and the content of methimazole was determinated indirectly through determinating the surplus content of Fe (Ш) in the system.The maximum absorption wavelength of chromogenic system was 663 nm, good linear relationship was obtained between A and the concentration of methimazole in the range of 3.2~12.8μg·mL^-1,the equation of the linear regression was A=-0.1849+57.277ρ (mg·mL^-1),with a linear correlation coefficient was 0.9998.This proposed method had been successfully applied to determinate of methimazole in real pharmaceutical.

Abstract: Honey was a particular matrix with a variety of composition and origin, which lead to different degree of matrix effect on analytes. As a rule, the matrix-matched calibration curve from blank honey was adopted to quantifying analyte in a batch. This paper investigated matrix effect on sulfonamide in four honey samples by high-performance liquid chromatography hyphenated with mass spectrometry detection. The main goal was to check whether matrix-matched calibration curve obtained from a random blank honey could match the real samples in character within current recommended acceptance criteria. It was found that analyte recovery from true matrix-matched standard calibration curve ranged 87.7-117.3%, whereas recovery from surrogate matrix-matched calibration curves gave a very wide range from 54.3 to 150.2%, far beyond the acceptance criteria. So it was perhaps not feasible to use a surrogated blank sample to prepare matrix-matched calibration curve for quantifying analyte, particularly for largely diverse honey samples in a batch. To reduce error from inter-sample matrix effect, the best solution seemed to use internal standard or standard addition.

Abstract: The stain of Fusarium sp. used in 4-chlorophenol (4-CP) degradation was isolated in our laboratory. The effects of pH, Cu²⁺ concentration, carbon source on 4-CP degradation rate by Fusarium sp. were investigated. The kinetic equation of 4-CP biodegradation was discussed. It was concluded that Fusarium sp. could grow with 4-CP as the sole carbon and energy source. 4-CP concentration of 50mg/L in the Cu²⁺ concentration of 3mg/L could be degraded completely. The capacity of 4-CP degradation was effectively enhanced by the addiction of phenol. Phenol concentration of 200 mg/L in the pH 7 and the Cu²⁺ concentration of 3 mg/L could be degraded completely. Cu²⁺ at high concentration might reduce the biodegradation rate of 4-CP. The kinetic equation of 4-CP biodegradation could well accord with the zero order equation for 4-CP as the sole carbon source with Cu²⁺ coexistence by Fusarium sp..

Abstract: This paper investigated several influencing factors for the preparation of solid alcohol, including the amount of raw materials used such as stearic acid and copper nitrate and so on, and the temperature, etc. Through single factor experiments, the main influence factors of preparing solid alcohol were determined. And, on this basis, in view of three remarkable influence factors: the stearic acid amount used, the copper nitrate amount used and the temperature, the orthogonal experiment was carried out. Finally, the optimal preparation conditions were determined as follows: 25ml industrial alcohol, 1.3g stearic acid, 1.2ml 10% copper nitrate solution, at 75°C, pH 8, the cooling way is gradual cooling with no refluxing.

Abstract: An effective resolving agent, (D)-dibenzoyl tartaric acid (2b), was screened to yield direct resolution of (S)- ethyl nipecotate (1) with high optical purity and yield. Molecular recognition was studied by 1H NMR, IR, DSC and single crystal diffraction of the pair of diastereomeric salts. The less-soluble salt formed a supra molecular structure by enantio differentiating self-assembly.

Abstract: In order to study the formation conditions of CO2-gas hydrate and screen appropriate inhibitors, DBR hydrate test device was put into use .Under 0~15MPa and -10~38°C ,the production conditions of natural gas hydrate was measured when the content of CO2 in the system was 10%,30%,50%,70%,90% respectively .According to prior work ,methanol and ethylene glycol was selected to be the inhibitors .Different concentrations of inhibitors were taken into test to gain the generation conditions of the hydrate .The results of the expriment show that the generation temperature of hydrate increase along with the raise of CO2 content .As an inhibitor ,21.8% of the ethylene glycol could lower the generation temperature about 6°C while 43.6% of it could reduce by 7-10°C .By contrast ,16.5% of methanol could lower the generation temperature about 10-16°C in the low-pressure region ,while 34.6% of it could reduced the generation temperature in all pressure region .It can be drawn that Methanol shows its better character ,but toxicity .The effects of ethylene glycol were relatively poor ,however ,little pollution .Therefore ,supposing the well-developed clearance recovery technology ,methanol was recommended .

Abstract: Hollow BiVO₄ microspheres composed of nanosized particles were successfully prepared via a simple hydrothermal reaction route at 170C for 12 h. The crystal structures, morphologies, and optical properties of the as-prepared samples were characterized by X-ray powder diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and UV-visible absorption spectra (UV-vis). Simulated Sun-light induced photocatalytic degradation of Rhodamine B by hollow BiVO₄ microspheres has been investigated, and the results show the hollow structures with excellent photocatalytic activity.