scholarly journals Dissipation, residues analysis and risk assessment of metconazole in grapes under field conditions using gas chromatography–tandem mass spectrometry

2021 ◽  
Vol 13 (4) ◽  
pp. 84-97
Author(s):  
Wang Guo ◽  
Yuling Chen ◽  
Hui Jiao ◽  
Deyu Hu ◽  
Ping Lu
Keyword(s):  
Mass Spectrometry ◽  
Risk Assessment ◽  
Gas Chromatography ◽  
Tandem Mass Spectrometry ◽  
Hazard Index ◽  
Field Conditions ◽  
Tandem Mass ◽  
Dietary Risk ◽  
Chromatography Tandem Mass Spectrometry ◽  
Relative Standard

Metconazole (MEZ) is widely used in prevention and control of fruit and vegetable diseases. Here, a simple and reliable gas chromatography–tandem mass spectrometry (GC-MS/MS) method, using modified QuEChERS (“quick, easy, cheap, effective, rugged and safe”) extraction method, was developed for determining the dissipation and residue of MEZ in grapes and soil, and the dietary risk of MEZ residues in grapes was evaluated for Chinese people. The average recoveries of MEZ in two matrices were 80.72–100.36% with relative standard deviations of 1.56–6.16%. The same limits of detection and quantification in grapes and soil were 0.0006 mg/kg and 0.002 mg/kg, respectively. Under field conditions, the half-life of MEZ dissipation in grapes ranged from 11.75 to 20.39 days. The final residues of MEZ in grapes and soil ranged from 0.002 mg/kg to 0.19 mg/kg at pre-harvest intervals of 7, 14 and 21 days. The whole dietary risk assessment indicated acute hazard index and hazard quotient to be less than 1, implying the risk of MEZ was acceptable. This is the first study conducted on the dissipation, residue analysis and risk assessment of MEZ in grapes, thus providing reference for the detection and risk assessment of MEZ in other agricultural products.

scholarly journals Gas Chromatography-Tandem Mass Spectrometry Method for Selective Detection of 2-Nitropropane in Mainstream Cigarette Smoke

2019 ◽  
Vol 28 (7) ◽  
pp. 300-309
Author(s):  
Gala M. Chapman ◽  
Juliana Giraldo Junco ◽  
Roberto Bravo Cardenas ◽  
Clifford H. Watson ◽  
Liza Valentín-Blasini
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Tandem Mass Spectrometry ◽  
Cigarette Smoke ◽  
Limit Of Detection ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Relative Standard ◽  
Standard Deviations ◽  
Mainstream Cigarette Smoke

SummaryAlthough 2-nitropropane is a potentially harmful compound present in cigarette smoke, there are few fully-validated, modern methods to quantitate it in mainstream cigarette smoke. We developed an isotope dilution gas chromatography-tandem mass spectrometry (ID-GC-MS/MS) method for the detection of 2-nitropropane in mainstream cigarette smoke. The vapor fraction of mainstream cigarette smoke was collected in inert polyvinyl fluoride gas sampling bags and extracted with hexanes containing isotopically labeled internal standard, then purified and concentrated via solid-phase extraction using a normal phase silica adsorbent and a 100% dichloromethane eluant. This method is sensitive enough to measure vapor phase 2-nitro-propane concentrations in the nanogram range, with a 19 ng per cigarette method limit of detection. Product variability estimated from the analysis of 15 cigarette products yielded relative standard deviations ranging from 5.4% to 15.7%, and estimates of precision from two quality control products yielded relative standard deviations of 9.49% and 14.9%. Under the Health Canada Intense smoking regimen, 2-nitropropane in machine-generated mainstream smoke from 15 cigarette products ranged from 98.3 to 363 ng per cigarette.

scholarly journals Analysis of Pesticide Residues in Mixed Fruit and Vegetable Extracts by Direct Sample Introduction/Gas Chromatography/Tandem Mass Spectrometry

2000 ◽  
Vol 83 (3) ◽  
pp. 680-697 ◽  
Author(s):  
Steven J Lehotay
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Tandem Mass Spectrometry ◽  
Pesticide Residues ◽  
Sample Introduction ◽  
Breakdown Product ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Relative Standard ◽  
Direct Sample

Abstract Direct sample introduction (DSI), or “dirty sample injection,” was investigated in the determination of 22 diverse pesticide residues in mixed apple, green bean, and carrot extracts by benchtop gas chromatography/tandem mass spectrometry (DSI/GC/MS–MS). The targeted pesticides, some of which were incurred in the samples, included chlorpyrifos, azinphos-methyl, parathion-methyl, diazinon, terbufos, p,p′-DDE, endosulfan sulfate, carbofuran, carbaryl, propargite, bifenthrin, dacthal, trifluralin, metalaxyl, pendimethalin, atrazine, piperonyl butoxide, diphenylamine, vinclozolin, chlorothalonil, quintozene, and tetrahydrophthalimide (the breakdown product of captan). The analytical DSI method entailed the following steps: (1) blend 30 g sample with 60 mL acetonitrile for 1 min in a centrifuge bottle; (2) add 6 g NaCl and blend 30 s; (3) centrifuge for 1–2 min; (4) add 5 mL upper layer to 1 g anhydrous MgSO4 in a vial; and (5) analyze 11 μL extract, using DSI/GC/MS–MS. Sample cleanup is not needed because GC/MS–MS is exceptionally selective for the targeted analytes, and nonvolatile coextracted matrix components do not contaminate the injector or the GC/MS–MS system. Average recoveries of the pesticides were 103 ± s7% with relative standard deviations of 14 ± 5% on average, and limits of detection were <2 ng/g for nearly all pesticides studied. The DSI/GC/MS–MS approach for targeted pesticides is quantitative, confirmatory, sensitive, selective, rugged, rapid, simple, and inexpensive.

scholarly journals Method Validation and Dissipation Behaviour of Dimethyl Disulphide (DMDS) in Cucumber and Soil by Gas Chromatography-Tandem Mass Spectrometry

2019 ◽  
Vol 16 (22) ◽  
pp. 4493
Author(s):  
Kaium ◽  
Cao ◽  
Liu ◽  
Xu ◽  
Dong ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Tandem Mass Spectrometry ◽  
Kinetic Equations ◽  
Tandem Mass ◽  
Order Kinetic ◽  
Multiwalled Carbon ◽  
Dimethyl Disulphide ◽  
Chromatography Tandem Mass Spectrometry ◽  
Relative Standard

In this study, a useful analytical method was developed and validated for measuring the residues of dimethyl disulphide (DMDS) in cucumbers and soil by gas chromatography-tandem mass spectrometry (GC-MS/MS). The dissipation dynamics and residual levels of DMDS in cucumber and soil were also studied in Shandong, Jilin, and Hebei provinces by using this method. Dichloromethane was selected and used as the extraction solvent to extract the target pesticide from the soil and cucumber samples. The soil and cucumber samples were cleaned up by the combination of multiwalled carbon nanotubes (MWCNT) and biochar. The average recoveries of the DMDS in cucumbers and soil were in the range of 84–101.5%, with relative standard deviations (RSD) of 0.7–4.9%, when they spiked at 0.05, 0.5, and 5 mg/kg DMDS respectively. The limit of quantification (LOQ) of this method was 0.05 mg/kg. First-order and second-order kinetic equations were used to fit dissipation data. Results show that the half-lives of DMDS in the soil at Shandong, Jilin, and Hebei were 1.63–4.47 days, 1.96–6.49 days, and 1.35–2.51 days, respectively. The final residues of DMDS were less than 0.05 mg/kg in cucumbers and 0.36 mg/kg in the soil. The dissipation rates of DMDS in different soils were different. The method provides a basis for the risk assessment of DMDS in cucumber and soil.

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