Dissipation pattern and safety evaluation of cartap and its metabolites during tea planting, tea manufacturing and brewing.

There are few studies for risk assessment of cartap and its metabolites, although cartap is easily transformed into metabolites which could induce higher toxicity. This study aimed to investigate the dissipation pattern of cartap and its metabolites during tea planting, manufacturing and brewing for evaluating the safety of cartap pesticide. Cartap metabolites were identified using Q-Exactive Orbitrap mass spectrometry. Half-lives of cartap in fresh tea leaves ranged from 0.49 to 0.59 days. Cartap decreased rapidly with time, and it was degraded into nereistoxin and cartap monothiol during tea production chain. Cartap monothiol residues dissipated rapidly by 98% in three days during tea planting. Nereistoxin had a longer residual period than cartap and it dominated the total residue in made tea after tea manufacturing. Transfer rates of nereistoxin during tea brewing ranged from 78.24% to 121.56%. Therefore, we suggested sum of cartap and nereistoxin residues as maximum residual limits in tea.

Simultaneous determination of cartap and its metabolite in tea using hydrophilic interaction chromatography tandem mass spectrometry and the combination of dispersive solid phase extraction and solid phase extraction.

Risk assessment of cartap residue in tea should include the exposure of cartap and its metabolite due to rapid degradation of cartap into nereistoxin. Herein, a reliable method for determination of cartap and nereistoxin in tea was developed by hydrophilic interaction chromatography tandem mass spectrometry. Target compounds were extracted with water containing 1% formic acid and 5 mM ammonium formate. The use of dichloromethane effectively removed caffeine. Tea extracts were cleaned up by dispersive adsorbents of octadecylsilane and strong anion exchanger, then further purified using hydrophilic lipophilic balanced solid phase extraction cartridge. Isotopic internal standard was employed to calibrate the loss of analytes during sample preparation and compensate matrix effects. Method validation illustrated excellent linearity, with correlation coefficients (R2) higher than 0.999. Satisfactory recoveries of target compounds spiked in green tea, black tea and oolong tea ranged from 87.6% to 119.9% with intra- and inter-day precisions below 20%. Limits of quantification of cartap and nereistoxin were 10.0 µg kg-1, and limits of detection were 2.0 µg kg-1 for cartap and 4.0 µg kg-1 for nereistoxin. The developed method was applied to determine cartap and nereistoxin in thirty tea samples.

Rapid Colorimetric Detection of Cartap Residues by AgNP Sensor with Magnetic Molecularly Imprinted Microspheres as Recognition Elements.

The overuse of cartap in tea tree leads to hazardous residues threatening human health. A colorimetric determination was established to detect cartap residues in tea beverages by silver nanoparticles (AgNP) sensor with magnetic molecularly imprinted polymeric microspheres (Fe3O4@mSiO2@MIPs) as recognition elements. Using Fe3O4 as supporting core, mesoporous SiO2 as intermediate shell, methylacrylic acid as functional monomer, and cartap as template, Fe3O4@mSiO2@MIPs were prepared to selectively and magnetically separate cartap from tea solution before colorimetric determination by AgNP sensors. The core-shell Fe3O4@mSiO2@MIPs were also characterized by FT-IR, TEM, VSM, and experimental adsorption. The Fe3O4@mSiO2@MIPs could be rapidly separated by an external magnet in 10 s with good reusability (maintained 95.2% through 10 cycles). The adsorption process of cartap on Fe3O4@mSiO2@MIPs conformed to Langmuir adsorption isotherm with maximum adsorption capacity at 0.257 mmol/g and short equilibrium time of 30 min at 298 K. The AgNP colorimetric method semi-quantified cartap ≥5 mg/L by naked eye and quantified cartap 0.1⁻5 mg/L with LOD 0.01 mg/L by UV-vis spectroscopy. The AgNP colorimetric detection after pretreatment with Fe3O4@mSiO2@MIPs could be successfully utilized to recognize and detect cartap residues in tea beverages.

Inorganic selenium speciation analysis in Allium and Brassica vegetables by ionic liquid assisted liquid-liquid microextraction with multivariate optimization.

A highly sensitive vortex assisted liquid-liquid microextraction (VA-LLME) method was developed for inorganic Se [Se(IV) and Se(VI)] speciation analysis in Allium and Brassica vegetables. Trihexyl(tetradecyl)phosphonium decanoate phosphonium ionic liquid (IL) was applied for the extraction of Se(IV)-ammonium pyrrolidine dithiocarbamate (APDC) complex followed by Se determination with electrothermal atomic absorption spectrometry. A complete optimization of the graphite furnace temperature program was developed for accurate determination of Se in the IL-enriched extracts and multivariate statistical optimization was performed to define the conditions for the highest extraction efficiency. Significant factors of IL-VA-LLME method were sample volume, extraction pH, extraction time and APDC concentration. High extraction efficiency (90%), a 100-fold preconcentration factor and a detection limit of 5.0ng/L were achieved. The high sensitivity obtained with preconcentration and the non-chromatographic separation of inorganic Se species in complex matrix samples such as garlic, onion, leek, broccoli and cauliflower, are the main advantages of IL-VA-LLME.

Combined determination and confirmation of ethylenethiourea and propylenethiourea residues in fruits at low levels of detection.

In this work, a new method for the determination of ethylenethiourea (ETU) and propylenethiourea (PTU) in fruits and vegetables is presented. Different extraction and purification techniques, including matrix solid phase dispersion (MSPD) and solid-liquid extraction (SLE), followed by a clean-up step by solid phase extraction (SPE), were compared. The determination of ETU and PTU was performed by high performance liquid chromatography with diode array detection (HPLC/DAD) or by gas chromatography with mass spectrometry detection (GC/MS). The effect of several parameters on the extraction, separation and detection was studied. The proposed method based on solid-liquid extraction with acetonitrile, clean-up with Envicarb II/PSA cartridges and subsequent analysis by HPLC/DAD was characterised and applied to the analysis of fruits and vegetables from different countries. Analytes recoveries were between 71% and 94% with relative standard deviations (RSDs) ranging from 8% to 9.5%. Quantification limits obtained for ETU and PTU with the HPLC/DAD method were 7 and 16 µg kg⁻¹ in strawberries (fresh weight), respectively. For apples, they were 11 and 25 µg kg⁻¹, respectively.

Identification of new, odor-active thiocarbamates in cress extracts and structure-activity studies on synthesized homologues.

New, odorant nitrogen- and sulfur-containing compounds are identified in cress extracts. Cress belongs to the botanical order Brassicales and produces glucosinolates, which are important precursors of nitrogen- and sulfur-containing compounds. Those compounds often present low perception thresholds and various olfactive notes and are thus of interest to the flavor and fragrance chemistry. When the study of organonitrogen and organosulfur compounds is undertaken, Brassicale extracts are one of the matrices of choice. Cress extracts were studied by analytical (GC-MS, GC-FPD) and chemical (fractionation) means to identify new interesting odorant compounds. Two compounds that have never been reported in cress extracts, containing both nitrogen and sulfur, were discovered: N-benzyl O-ethyl thiocarbamate and N-phenethyl O-ethyl thiocarbamate. These two molecules being of organoleptic interest, their homologues were synthesized and submitted to organoleptic tests (static and GC-sniffing). Their odors evolve from garlic and onion over green, mushroom- and cress-like to fresh, spearmint-like. This paper presents the origin, chemical synthesis, and organoleptic properties of a series of O-alkyl thiocarbamates.

Modeling of methyl isothiocyanate air concentrations associated with community illnesses following a metam-sodium sprinkler application.

BACKGROUND: A series of illnesses occurred in Earlimart, CA on November 13, 1999 following a metam-sodium sprinkler application to a potato field on the southern edge of the town. METHODS: Case information was obtained from direct interviews, from illness complaints filed with state or county agencies, or from illness reports filed by community physicians for 173 subjects. Air concentrations of the by-product methyl isothiocyanate (MITC) during the episode were estimated based upon the Industrial Source Complex Short-Term (ISC3) air dispersion model, estimates from prior metam-sodium monitoring studies, and data from weather stations in two adjoining communities. RESULTS: Weather station data indicated that the November 13th incident corresponded with a temperature inversion at approximately 5:00 p.m. and a shift in the direction of prevailing wind from northwest to southeast. On the edge of Earlimart, 1-hr time weighted average (TWA) MITC concentration estimates ranged from 0.5 to 1 ppm. Of the 173 subjects, 170 had MITC-compatible symptoms, including eye or upper respiratory irritation (77.6%), non-specific systemic symptoms (64.7%), and lower respiratory symptoms (20.0%). 78.2% were exposed within 0.5 miles of the northern edge of the treated field where average 1 hr MITC concentrations exceeded the 800 ppb ocular irritation threshold. CONCLUSIONS: ISC3 modeling is a useful means of evaluating MITC concentrations for illness episodes when industrial hygiene assessment is not possible.