Chun Liang Yang

Determination of Imidacloprid, Carbendazim and Thiabendazole Residues in Vegetables and Fruits by HPLC

The aim of this work was to establish a method that the residues of imidacloprid,carben-dazim and thiabendazole in fruits and vegetables were determined by HPLC.Acetonitrile was edded in the sample for extraction solvent, and using sodium chloride for absorbing water of the sample,then purified by NH2 solid phase extraction cartridge, the sample was detected by HPLC.Under the selected conditions,the detection limits of imidacloprid, carbendazim, thiabendazole were 0.002 mg/kg,0.003 mg/kg and 0.003 mg/kg respectively.Tests for recovery were made by addition of three pesticidess standards at three different concentration levels (0.1, 0.5 and 1.0 mg/kg) to the blank sample.The mean recovery rates of imidacloprid, carbendazimand thiabendazole were87.0%~99.2%,82.0%~96.0% and 80.0%~95.0% respectively , and the relative standard deviations were 0.52%~6.80%.The sensitivity, accuracy and precision of this method were able to meet the requirements for pesticide residue analysis.

Determination of Chlorbenzuron Residues in Tea by UPLC-MS/MS

Residual amount of chlorbenzuron derived from tea was determined by UPLC-MS/MS. Chlorbenzuron was extracted with acetonitrile, purified by carbon/NH2 SPE cartridge, and then determined by ultra high-performance liquid chromatography with tandem mass spectrometry. The values o f lower limit of determination (10 S/ N) of 1.0 ug/kg-1 was found for Chlorbenzuron.Linear relationships in the range within 200 ug/L-1 was found . Recovery and precision of the method was tested by standard addition method at 3 concent ration levels. Results obtained was as follows: recovery 79.2 % - 89.6 %; RSD ( n= 6) of repeatability 0.72 % -5.85 %.It is suitable for the determination of chlorbenzuron residual in tea.

The Natural Rubber/Zinc Oxide Nanocomposites: Its Morphology, Mechanical and Thermal Decomposing Properties

Natural rubber /Zinc Oxide (NR/ZnO) nanocomposites are fabricated by blending natural rubber latex with aqueous suspension of nanoZnO particles. Its morphology and thermal/thermooxidative ageing resistance are investigated with scanning electron microscopy (SEM) and thermogravimetric analyzer (TGA). The results show that the mechanical properties of NR is greatly improved by the incorporation of nanoZnO, nanoparticles, which are homogenously distributed throughout NR matrix as nanoclusters with an average size of 80 nm when the ZnO loading is less than 4 wt%. The thermal/thermooxidative aging resistance of NR/ZnO nanocomposites is compared to the pure NR. It is found that the introduction of nanoZnO has no obvious impact to the thermal decomposing properties of NR matrix. ZnO/NR composites possess excellent antibacterial effect.

Determination of Diflubenzuron Residues in Vegetables by UPLC-MS/MS

The conditions for detecting residues of diflubenzuron in vegetables by ultra high performance liquid chromatography tandem mass spectrometry were studied. The target was extracted with acetonitrile for 2 min with a homogenizer. The extaction was purifide by a conditioned Florisil SPE cartridge, and then was detected by ultra high-performance liquid chromatography with tandem mass spectrometry. The average recovery was in the range from 87.8 %- 99.2 % at spike levels of 0.1, 1.0 and 10 mg/kg in vegetables, and relative standard deviations was in the range of 4.2 %-8.9 %. The proposed method is fast, simple, sensitive and accurate.

Determination of Imidacloprid Residues in Chinese Cabbage by UPLC-MS/MS

A method for determination of imidacloprid in Chinese Cabbage was established by using UPLCMS/MS. and the samples are extracted with acetontrile,and the extract is cleaned up by Florisil SPE cartridges and evaporated.Choromatographic separation was performed on a C18 column,and determined by UPLC-MS/MS.The external standard calibration curves were used for quantification. The results showed that a good linear correlation was obtained in the range of 0.005-0.1ug/mL. The limit of quantif icat ion w as 0. 008 mg/ kg .The average recoveries and the relative standard deviations were in the range of 84.9 %~92.7 % and 0.9 %~6.2 %, respectively. It is applicable to the determination of imidacloprid redidue in Chinese cabbage.

Study on Natural Rubber Quality of Micro-Cut Tapping with Gas-Stimulation

The natural rubber samples produced by conventional tapping methods were used as a control, then analyzed the dry rubber property of natural rubber, the dynamic property and Physical & mechanical property of vulcanized rubber using Rubber processing analyzer and Thermogravimetric Analyze the difference between the properties of dry rubber and vulcanized rubber produced by Micro-cut Tapping with Gas-stimulation. The results indicated that the tensile strength, tear strength elastic modulus of dry rubber that produced by Micro-cut Tapping with Gas-stimulation are respectively 20%, 7% lower than the control. The protein content of dry rubber materials produced by Micro-cut Tapping with Gas-stimulation is 16.7% higher than control group.

Determination of Imidacloprid, Acetamiprid, Thiabendazole and Carbendazim Residues in Edible Fungi by HPLC

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.

Determination of Residues of Malachite Green and Leucomalachite Green in Chinese Soft-Shelled Turtle (Pelodiscus sinensis) Muscle by Ultra-High Performance Liquid Chromatography-Mass Spectrometry

A method for the determination of residues of malachite green and leucomalachite green in Chinese soft-shelled turtles (Pelodiscus sinensis) muscle by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was established. The samples extracted with acetonitrile, and clean up on a neutral alumina SPE cartridge, separated on a C18 column using acetonitrile-5mmol/L ammonium acetate as mobile phase, and then detected under multiple reaction monitoring mode.The method showed a good linearity for all the analysts over the range of 0.1-50μg/L with r20.999.The detection limits of malachite green and leucomalachite green were 0.10 and 0.12μg/kg respectively. The recoveries ranged from 84.9 % to 93.8% at three spiked concentrations with the relative standard deviations lower than 5%. The results shows that this method has the advantages of easy to operate, fast to perform,with high sensitivity and accuracy, and it is suitable for detection of residues of malachite green and leucomalachite green in Chinese soft-shelled turtle (Pelodiscus sinensis).

Multiresidue Determination of Avermectins in Plant-Derived Food by UPLC-MS/MS

The objective of this study was to propose a method that the residues of avermectins (Abamectin, Emamectin Benzoate, Ivermectin, Eprinomectin and Doramectin) derived from the food plant were determined by UPLC-MS/MS. The avermectins were extracted with acetonitrile, purified by Alumina B or GCB/NH2 SPE cartridge, and then determined by ultra high-performance liquid chromatography with tandem mass spectrometry. Tests for recovery (Recovery rate: 80.6%～99.8%, RSDs: 0.22%～6.4%) were made by addition of avermectin standards at three different concentration levels (4, 20 and 100μg/kg) to five kinds of food plant as matrixes. The sensitivity, accuracy and precision of this method were able to meet the requirements for pesticide residue analysis.