Splitless large-volume GC-MS injection for the analysis of organophosphorus and organochlorine pesticides in vegetables using a miniaturised ethyl acetate extraction (original) (raw)
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Analyst, 2000
A simple, rapid and sensitive multiresidue method has been developed for the determination of ten organophosphorus and organochlorine pesticides, commonly used in crop protection. The analysis uses a miniaturised extraction with ethyl acetate followed by large volume injection (10 mL) GC-EI-MS analysis in SIM (selective ion monitoring) mode. Sensitivity and selectivity of the method were acceptable with limits of detection (LODs) lower than 0.01 mg kg 21 , except for endosulfan a and b (0.05 mg kg 21). Average recoveries of between 63-99% were obtained and good linearity was observed in the range from 0.01 to 1.00 mg kg 21. Repeatability and reproducibility studies yielded relative standard deviations lower than 20% in all the cases. The method was applied to the analysis of 110 tomato, pepper and cucumber samples, as part of the monitoring programme of the Association of Producers and Exporters of Fruits and Vegetables of Almería.
seven organophosphorous pesticides (methamidophos, diazinon, dimethoate, parathion-methyl, chlorpyriphos, malathion and tetrachlorvinphos) in vegetables (potato, onion, tomato, red pepper, lettuce and green onion), cultivated in José María Vargas County, Táchira State in the Bolivarian Republic of Venezuela, was developed. The pesticides were extracted with ethylacetate/acetone at two concentrations (80:20 and 90:10 v/v). Final determination of the analytes was made by gas chromatography with nitrogen-phosphorus detection. The identification of compounds was based on the retention time. The extraction efficiency was evaluated by the fortification of vegetables samples, and recovery studies were performed at two levels of enrichment (0.05 and 0.1 mg.kg-1). Recoveries obtained ranged from 70% to 110% with relative standard deviations lower than 12%. The method showed good linearity over the range assayed 0.01 and 1.0 mg kg-1 and the detection limits were between 0.011 and 0.032 mg.kg-...
Journal of the Brazilian Chemical Society, 2004
Os pesticidas organofosforados são freqüentemente aplicados no cultivo de tomate no Brasil. No presente trabalho uma metodologia analítica foi desenvolvida e validada para a quantificação de resíduos dos pesticidas organofosforados acefato, chlorpyrifós, malation, metamidofós and paration metílico em tomate, empregando Cromatografia Gasosa com Detector de Nitrogênio e Fósforo (GC-NPD). A possibilidade de ocorrência de efeito matriz foi estudada. As curvas analíticas, preparadas nos extratos da matriz, foram lineares de 0,006 até 0,80 mg L -1 . Os estudos de precisão forneceram resultados com RSD <15%. As recuperações dos pesticidas, obtidas com as curvas preparadas no extrato da matriz, foram entre 88 e 118%. Com o procedimento proposto foram obtidos limites de quantificação entre 0,0132 e 0,135 mg kg -1 .
Chemical Industry & Chemical Engineering Quarterly, 2010
Three rapid, simple, reproducible and sensitive spectrophotometric methods (A, B and C) are described for the determination of two organophosphorus pesticides, (malathion and dimethoate) in formulations and vegetable samples. The methods A and B involve the addition of an excess of Ce 4+ into sulphuric acid medium and the determination of the unreacted oxidant by decreasing the red color of chromotrope 2R (C2R) at a suitable λ max = 528 nm for method A, or a decrease in the orange pink color of rhodamine 6G (Rh6G) at a suitable λ max = = 525 nm. The method C is based on the oxidation of malathion or dimethoate with the slight excess of N-bromosuccinimide (NBS) and the determination of unreacted oxidant by reacting it with amaranth dye (AM) in hydrochloric acid medium at a suitable λ max = 520 nm. A regression analysis of Beer-Lambert plots showed a good correlation in the concentration range of 0.1-4.2 μg mL −1 . The apparent molar absorptivity, Sandell sensitivity, the detection and quantification limits were calculated. For more accurate analysis, Ringbom optimum concentration ranges are 0.25-4.0 μg mL −1 . The developed methods were successfully applied to the determination of malathion, and dimethoate in their formulations and environmental vegetable samples.
… of Chromatography A, 1992
A sensitive method for the high-performance liquid chromatographic determination of five organophosphorus pesticides (paraoxon, methyl-parathion, ethyl-parathion, guthion and fenitrothion) in fruits and tap and river water samples is described. For the determination of pesticides in fruits a simple and rapid sample preparation procedure was developed that allowed pesticides to be determined at 50-100 pg/kg levels with recoveries ranging from 83 to 118% and relative standard deviations below 6%. The determination of pesticide residues in surface water samples was also successfully accomplished. Concentrations at sub-ppb levels can be measured by using a solid-phase concentration step, the recoveries being over 80%. In analyses of both fruits and surface waters, the sensitivity levels achieved were 2-10 times lower than legal limits admitted in the European Economic Community .
2009
In the existing study, an effort has been made to evaluate and determine residues of three pesticides in vegetables, belonging to Organophosphate group, which was extensively used in the Southern part of Punjab province in Pakistan. Triazophos, profenofos and chlorpyrifos Organophosphorus insecticides, were commonly used on the summer vegetables like: egg plant, Pumpkins and okra cultivated in study area. Vegetables were analyzed for pesticide residues using multiresidue analysis by High-Performance Liquid Chromatography (HPLC) equipped with UV detector. It was observed that 33.0% of the samples were contaminated with any of the above three pesticides. The results showed that 8% of the samples tested contained residues higher than the MRLs. Based on observations made in these studies; it is proposed that more extensive monitoring investigations covering all vegetables from different agro-climatic regions of the state be carried out to find the exact position of pesticide residues.
Journal of Chromatography A, 2003
It was demonstrated that four out of six of the very polar organophosphorus pesticides (OPs), i.e. acephate, methamidophos, monocrotophos, omethoate, oxydemeton-methyl and vamidothion, could not be extracted from water using commonly available SPE cartridges. In addition, GC analysis on all six compounds was found to be troublesome due to their polar and thermolabile character. This initiated the development of an alternative highly sensitive and selective method for the determination of the above mentioned very polar OPs in water, based on LC-MS. Large volume (1 ml) water samples were directly injected onto an RP18 HPLC column with a polar endcapping. The latter was essential for obtaining retention and maintaining column performance under 100% aqueous conditions during the sampling. The compounds were ionized using atmospheric pressure chemical ionization and detected on a tandem mass spectrometer operated in multiple reaction-monitoring mode. The detection limits were in the range of 0.01-0.03 mg / l. Compared to conventional GC methods, the developed LC-MS procedure is very straightforward, fast and more reliable. This application demonstrates the applicability of LC-MS for analysis of polar OPs in surface, ground and drinking water, as a more favourable alternative to GC.
2020
In this paper, the technique of continuous sample drop flow microextraction (CSDF-ME) is developed by the addition of a narrow-necked conical vessel. In the developed technique, an organic solvent denser than water is used for the extraction of organophosphorus pesticides (OPPs) from fruit juice and river water, followed by analysis with GC-MS. Eight milliliters of the sample solution is pumped at 0.5 mL min −1 flow rate into 12.0 μL extraction solvent (chloroform) and placed in the narrow-necked conical vessel for extraction and pre-concentration processes. Under optimal condition, the enrichment factor (EF) and linearity are found to be in the range of 102–380 and 500.0 μg L −1 with correlation coefficient greater than 0.98, respectively. The detection limit is in the range of 0.3–1.0 μg L −1 and LOQ ranged from 2.0–5.0 μg L −1 . The relative standard division (RSD) of six replicate measurements for three different concentrations (i.e., 15.0, 50.0, 150.0 μg L −1 ) is 3.8–8.4%, 2.6...