scholarly journals Utilizing a Rapid Multi-Plug Filtration Cleanup Method for 72 Pesticide Residues in Grape Wines Followed by Detection with Gas Chromatography Tandem Mass Spectrometry

Foods ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2731
Author(s):  
Shaowen Liu ◽  
Aijuan Bai ◽  
Le Song ◽  
Nan Zou ◽  
Yongtao Han ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Pesticide Residues ◽  
White Wine ◽  
Optimization Strategy ◽  
Pure Solvent ◽  
Relative Standard ◽  
The Matrix ◽  
Cleanup Procedure ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

A convenient and fast multi-residue method for the efficient identification and quantification of 72 pesticides belonging to different chemical classes in red and white grape wines has been developed. The analysis was based on gas chromatography tandem quadrupole mass spectrometric determination (GC–MS/MS). The optimization strategy involved the selection of the amount of multi-walled carbon nanotubes (MWCNTs) and the number of cleanup procedure cycles for multi-plug filtration cleanup (m-PFC) to achieve ideal recoveries and reduce the sample matrix compounds in the final extracts. The optimized procedure obtained consistent recoveries between 70.2 and 108.8% (70.2 and 108.8% for white wine, and 72.3 and 108.4% for red wine), with relative standard deviations (RSDs) that were generally lower than 9.2% at the three spiking levels of 0.01, 0.05 and 0.1 mg/kg. The linearity was studied in the range between 0.002 and 0.1 mg/kg using pesticide standards prepared both in pure solvent and in the presence of the matrix, showing coefficients of determination (R2) higher than 0.9495 for all the pesticides. To improve accuracy, matrix-matched calibration curves were used for calculating the quantification results. Finally, the method was used successfully for detecting pesticide residues in commercial grape wines.

scholarly journals A Novel Composite with Structural Health Monitoring Functionality via 2D and 3D Impedance Mapping Topography

2021 ◽  
Vol 11 (4) ◽  
pp. 1647
Author(s):  
Georgios Foteinidis ◽  
Alkiviadis S. Paipetis
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Structural Integrity ◽  
Carbon Fabric ◽  
Structural Health ◽  
The Matrix ◽  
Junction Points ◽  
Sinusoidal Electric Field ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

We report the transformation of a conventional composite material into a multifunctional structure able to provide information about its structural integrity. A purposely positioned grid of carbon fabric strips located within a glass fibre laminate in alternating 0/90 configuration combined with a ternary nanomodified epoxy matrix imparted structural health monitoring (SHM) topographic capabilities to the composite using the impedance spectroscopy (IS) technique. The matrix was reinforced with homogenously dispersed multi-walled carbon nanotubes (MWCNTs) and carbon black (CB). A sinusoidal electric field was applied locally over a frequency range from 1 Hz to 100 kHz between the junction points of the grid of carbon fabric strips. The proposed design enabled topographic damage assessment after a high-velocity impact via the local monitoring of the impedance. The data obtained from the IS measurements were depicted by magnitude and phase delay Bode plots and Nyquist plots. The impedance values were used to create a 2D and a multi-layer (3D) contour topographical image of the damaged area, which revealed crucial information about the structural integrity of the composite.

Simultaneous Determination of Eight New Generation Amide Insecticide Residues in Complex Matrix Agri-food by Multi-walled Carbon Nanotube Cleanup and UPLC-MS/MS

2021 ◽  
Author(s):  
Tao Lin ◽  
Xinglian Chen ◽  
Li Wang ◽  
Haixian Fang ◽  
Maoxuan Li ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Simultaneous Determination ◽  
High Performance ◽  
Rapid Determination ◽  
Complex Matrix ◽  
Limit Of Quantification ◽  
Relative Standard ◽  
The Matrix ◽  
Multi Walled Carbon Nanotubes

Abstract The simultaneous determination method of 8 amide pesticides by multi-walled carbon nanotubes (MWCNs) cleanup, combined with QuEChERS method and ultra-high performance liquid chromatography-triple quadrupole tandem mass spectrometry has been developed and successfully applied in complex matrix such as green onions, celery, leeks, citrus, lychees, avocado. The matric effect of MWCNs is optimized and compared with QuEChERS materials. The results show that MWCNs can effectively reduce the matrix effect in sample extraction. The mass spectrometry is optimized, through their chemical structure skeletons, the ESI+ and ESI- mode are simultaneously scanned in the method. The coefficient (r) is greater than 0.9990, the limit of quantification ranges from 0.03 to 0.80 μg/kg, the recovery rate ranges from 71.2% to 120%, and the relative standard deviation (RSD) ranges from 3.8% to 9.4%. The method is fast, simple, sensitive, and has good purification effect. It is suitable for the rapid determination of amide pesticides in complex matrix agri-food.

Determination of Chlorinated Pesticide Residues in Wheat by Electron Capture Gas Chromatography

1966 ◽  
Vol 49 (4) ◽  
pp. 768-772
Author(s):  
J G Saha
Keyword(s):  
Gas Chromatography ◽  
Petroleum Ether ◽  
Electron Capture ◽  
Pesticide Residues ◽  
Soxhlet Extraction ◽  
Cleanup Procedure ◽  
Ground Wheat

Abstract Electron capture gas chromatography has been used to measure the efficiency of an extraction and cleanup procedure for chlorinated pesticide residues in wheat. Soxhlet extraction of ground wheat with acetonitrile, followed by partition into petroleum ether and cleanup on a magnesia-Celite column has been found adequate for the determination of heptachlor, aldrin, dieldrin, and endrin in concentrations as low as 5 ppb. Recoveries of aldrin, dieldrin, and endrin ranged from 98 to 104%, while those of heptachlor were 84–92%.

Capillary Effect of Multi-Walled Carbon Nanotubes Suspension in Composite Processing

2008 ◽  
Vol 8 (4) ◽  
pp. 1669-1678
Author(s):  
Zhihang Fan ◽  
Suresh G. Advani
Keyword(s):  
Carbon Nanotubes ◽  
Interlaminar Shear Strength ◽  
Fiber Bundles ◽  
High Permeability ◽  
Fiber Preform ◽  
Capillary Action ◽  
The Matrix ◽  
Multi Walled Carbon Nanotubes ◽  
Interlaminar Shear ◽  
Walled Carbon Nanotubes

Carbon nanotubes (CNTs) do have the potential to improve the interlaminar shear strength (ILSS) of composites if they can be successfully integrated into the matrix as it infuses into the fiber preform. The infusion under capillary action of Multi-Walled Carbon Nanotubes (MWNT)/Epoxy suspension with tubes of length 0.3∼1 μm in glass fiber bundles containing pores of the order of 5 nm∼100 μm was investigated. The influence of parameters such as suspension concentration, viscosity, porous media architecture, surface tension and contact angle were explored. It was found that filtering of the suspension is a major challenge for uniform infusion for concentrations beyond 0.5% MWNT by weight. This is even truer for fiber bundles that are compacted. Hence for successful manufacturing, new infusion techniques that rely on fabrics of high permeability will have to be developed to fabricate such nanocomposites.

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