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1

Application of deep eutectic solvents combined with vortex assisted dispersive liquid-liquid microextraction for five organophosphorus pesticides in juice and green tea beverage

Zhao Mingyu, Zhao Ercheng, Wu Junxue, Li Yuqi, Baotong Li

Acta Chromatographica

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2022

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Vol. 34, no. 1

53--60

EN

In this study, a new microextraction method based on hydrophobic deep eutectic solvents was developed for the extraction and preconcentration of organophosphorus pesticides from beverage samples. The hydrophobic deep eutectic solvents were synthesized from choline chloride and 4-chlorophenol. Main experimental parameters of the microextraction method were investigated to improve the extraction efficiency. The proposed method achieved a satisfactory linear range between 50 and 2,000 μg L-1 with coefficient of determination greater than 0.9939. The extraction recoveries and enrichment factor of five organophosphorus pesticides at three added levels ranged from 71.68 to 113.18% and 71.43–111.11 were obtained with the acceptable relative standard deviation ranged from 1.37 to 11.92%. Limits of detection and quantification were found to be 0.05–0.3 μg L-1 and 0.17–1 μg L-1, respectively. Finally, the methods were successfully applied for the determination of five organophosphorus pesticide in orange juice and green tea.

2

Development and validation of method for determination of organophosphorus pesticides traces in liver sample by GC-MS/MS-ion trap

Boneva Iskra, Yaneva Spaska, Danalev Dancho

Acta Chromatographica

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2021

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Vol. 33, no. 2

188--194

EN

A method for simultaneous determination of trace of four organophosphorus pesticides residues in animal liver samples has been developed and validated. This method is based on the preliminary sample preparation using extraction of target compound with a mixture of toluene-cyclohexane by means of up-to-date accelerated solvent extraction (ASE), liquid-liquid partitioning with acetonitrile and hexane, additional clean up step using QuEChERS method. Further the obtained analytes are determined by gas chromatography with ion-trap detector. The validation of the method is performed in accordance with the recommendations in Document SANTE/11945/2015 and it meets the acceptability criteria for precision, mean recovery and limits of quantification. The samples were investigated by analysing blank liver samples and samples spiked with the target analytes chlorpyrifos-methyl, parathion and pirimiphos-methyl at levels of 25, 50, and 75 ng/g and with diazinon at levels of 15, 30, and 45 ng/g. The recovery for all compounds were in the range from 73 to 104% which perfectly fit with requirements of documents and European legislations. The repeatability and within-laboratory reproducibility also reveal acceptable in documents coefficient of variation and uncertainty less than 20 and 18%, respectively. The limits of quantification were less than 3 ng/g for all compounds and allowed determination of residues below the maximum residue levels (MRLs) set in Regulation (EC) Nº 396/2005.

3

Study of the Effect of Air to Fuel ratio Parameter on the Organophosphorus – Pesticide Analysis by GC-FPD

Kilany A. Y., Elsayed M. A., Abd Elmegid M. K.

International Letters of Chemistry, Physics and Astronomy

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2014

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Vol. 17, iss. 3

236--248

EN

In the present contribution, sensitive and precise method for the quantification of Organophosphorus / Pesticides (Malathion and Dimethoate) in nanograms range has been developed. The performance of flame photometric detector (FPD), a selective detector (P&S-mode) that can be used in the analysis of organophosphorus compound, is evaluated in terms of sensitivity, selectivity and reproducibility. The performance of flame photometric detector was strongly depending on the absolute and relative flow rate of air and hydrogen gases. The optimum air-to-fuel ratio for detection of Malathion and Dimethoate was 0.4 and 0.3 (FPD-P mode). At this ratio, low picogram amounts of phosphor can be detected accurately (0.18 pgP) with a wide linear dynamic range of 0.18 pgP to 298 ngP. While, the optimum air-to-fuel ratio, for detection of Malathion and Dimethoate was 0.6 (FPD-S mode). In addition to, the method is precise with 4.5 % relative standard deviation (RSD). In conclusion, it could be proposed that this procedure can be recommended as a suitable method for the quantification of Malathion and Dimethoate in cases of acute poisoning.

4

Voltammetric determination of dimethoate in water

Pawlak M.K.

Chemia i Inżynieria Ekologiczna

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2006

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Vol. 13, nr 10

1115-1120

EN

Determinations of dimethoate in water by cathodic stripping differential pulse voltammetry on the hanging mercury drop electrode (HMDE) are discussed. As supporting electrolyte 0.04 mol dm-3 Britton-Robinson buffer was used. The effect of pH on the dimethoate peak current and peak potential was tested. Diniethoate creates two cathodic peaks at -0.53 and -0.67 V. A series of accumulation times and accumulation potentials at optimal pH equal to 12.5 were studied. The peak of dimethoate appearing at -0.53 V was chosen as the most promising from the analytical point of view. The calibration graph for accumulation time of 30 s and accumulation potential -0.25 V was linear in the range from 3 10 [to-7] to 40 10 [to -7] mol dm [to -3]. A possible interference with dimethoatc determination from the following ions: Cu(II), Zn(II), Pb(II), Cd((II), Co(II) and Ni(II) was examined. Discussed voltammetry method was used for determination of dimethoate in spiked water. The spiked water was passed through SPE-C18 Polar Plus column. For 6 samples spiked with 0.252 ppm of dimethoate, the relative standard deviation was 0.0412. The detection limit, estimated from 3 times the standard deviation, was 22.2 ppb.

PL

Do oznaczania dimetoatu w wodzie wykorzystano metodę katodowej woltamperometrii strippingowej w technice różnicowej pulsowej na wiszącej rtęciowej elektrodzie kroplowej. Jako elektrolit podstawowy zastosowano 0,04 mol - dm [do -3] roztwór buforowy Brittona-Robinsona. Zbadano wpływ pH na prąd i potencjał piku dimetoatu. Przy optymalnym pH ok. 12,5 wykonano krzywe zależności prądu piku dimetoatu od potencjału i czasu zatężania. Dimetoat daje dwa piki katodowe o potencjałach względem elektrody chlorosrebrowej równych -0,53 i -0,67V odpowiednio. Pik o potencjale -0,53V (P,) okazał się korzystniejszy z analitycznego punktu widzenia. W optymalnych warunkach (Ez=-0,25V, tz = 30 s) stwierdzono liniową zależność prądu piku P, od stężenia dimetoatu w zakresie stężeń: 3 do 40 o 10 [do -7] mol - dm [do -3]. Zbadano wpływ na oznaczanie dimetoatu następujących jonów metali: Cu(II), Zn(II), Pb(II), Cd(II), Co(II) i Ni(II). Przeprowadzono statystyczną ocenę wyników oznaczania dimetoatu w wodzie, wykorzystując ekstrakcję na kolumnach SPE-C18 Polar Plus. Względne odchylenie standardowe dla 6 próbek o stężeniu 0,252 ppm wynosiło 0,0412, granica wykrywalności: 22,2 ppb, a średni odzysk: 91,3 %.