Pesticide analysis in teas and chamomile by liquid chromatography and gas chromatography tandem mass spectrometry using a modified QuEChERS method: validation and pilot survey in real samples.

A multi-residue method for the determination of pesticides in tea using multi-walled carbon nanotubes as a dispersive solid phase extraction absorbent.

Gas chromatography coupled to atmospheric pressure ionization mass spectrometry (GC-API-MS): review.

1,4-Dioxane as an emerging water contaminant: State of the science and evaluation of research needs.

Determination of 400 pesticide residues in green tea leaves by UPLC-MS/MS and GC-MS/MS combined with QuEChERS extraction and mixed-mode SPE clean-up method.

The pesticide residues in exported and imported tea products must not exceed the maximum residue limits (MRLs) regulated by the import countries. Tea is a complex matrix that obfuscates the determination of pesticide residues. Many available methods for multiresidue pesticide analysis of tea are time-consuming and require many cleanup steps. The objective of this study was to develop a simple multiresidue method by using a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction and ion-trap GC/MS/MS, which can identify, confirm, and quantify pesticides in complex matrixes. A tea product was homogenized with water, and the pesticides were extracted with acetonitrile containing 1% acetic acid. The extract was subjected to centrifugation, initial cleanup with dispersive SPE (dSPE), solvent exchange, and final cleanup with dSPE. Diethyl-d10-parathion and triphenyl phosphate were used as the internal standard and surrogate, respectively. The final extract was injected into an ITQ 700 gas chromatograph/mass spectrometer. Quantitation of individual pesticides was based on matrix-matched calibration curves with a correlation coefficient of > 0.9930 for the 22 pesticides selected for the study. The recoveries of the 22 pesticides ranged from 78 to 115%, except those for diazinon (130%) and malathion (122%), with an average RSD of 8.7%. The LOD values of all of the pesticides, except for terbufos, were below the MRLs set by the European Union and Japan.

Determination of multiresidue pesticides in green tea by using a modified QuEChERS extraction and ion-trap gas chromatography/mass spectrometry.

A simplified sample preparation method in combination with gas chromatography–triple-quadrupole mass spectrometry (GC-MS/MS) analysis was developed and validated for the simultaneous determination of 227 pesticides in green tea, ginseng, gingko leaves, saw palmetto, spearmint, and black pepper samples. The botanical samples were hydrated with water and extracted with acetonitrile, magnesium sulfate, and sodium chloride. The acetonitrile extract was cleaned up using solid phase extraction with carbon-coated alumina/primary–secondary amine with or without C18. Recovery studies using matrix blanks fortified with pesticides at concentrations of 10, 25, 100, and 500 μg/kg resulted in average recoveries of 70–99% and relative standard deviation of 5–13% for all tested botanicals except for black pepper, for which lower recoveries of fortified pesticides were observed. Matrix-matched standard calibration curves revealed good linearity (r2 > 0.99) across a wide concentration range (1–1000 μg/L). Nine commercially...

Determination of Multiresidue Pesticides in Botanical Dietary Supplements Using Gas Chromatography-Triple-Quadrupole Mass Spectrometry (GC-MS/MS).

Introduction 1,4-Dioxane is used mainly as a stabilizer for 1,1,1-trichloroethane for transport in aluminum containers. It is an irritant to eyes and respiratory system and suspected of causing damage to nervous system, liver, and kidneys.1 In 2008, testing sponsored by the U.S. Organic Consumers Association found dioxane in almost half of tested organic personal-care products.1 Of the total 1.163 million pounds of 1,4-dioxane released into the U.S. environment in 1992, as reported to the Toxics Release Inventory, 680 thousand pounds (58.5%) were released into the atmosphere, 450 thousand pounds (38.7%) were released into surface waters, and 33 hundred pounds (2.8%) were released onto the land (TRI92 1994).2 In 2005, the New Hampshire Department of Environmental Services Waste Management Division started enforcement of an Ambient Groundwater Quality Standard reporting limit of 3 μg/L and trending towards a detection limit of 0.25 μg/L. 1,4-Dioxane has been detected in drinking water in the U.S. at a concentration of 1 μg/L. This application highlights the use of SIM/Full Scan to identify unknowns with a NIST library, while producing accurate results that meet EPA Method 522 requirements.

/pdf/determination-of-1-4-dioxane-in-drinking-water-by-gas-3cudvsym4y.pdf

Determination of 1,4-Dioxane in Drinking Water by Gas Chromatography/Mass Spectrometry (GC/MS) with Selected Ion Monitoring (SIM)

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Determination of multiresidue pesticides in green tea by using a modified QuEChERS extraction and ion-trap gas chromatography/mass spectrometry.

Determination of Multiresidue Pesticides in Botanical Dietary Supplements Using Gas Chromatography-Triple-Quadrupole Mass Spectrometry (GC-MS/MS).

Determination of 1,4-Dioxane in Drinking Water by Gas Chromatography/Mass Spectrometry (GC/MS) with Selected Ion Monitoring (SIM)