Validated dispersive liquid-liquid microextraction for analysis of organophosphorous pesticides in water (original) (raw)
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International Journal of Environmental Analytical Chemistry, 2010
A rapid and simple dispersive liquid-liquid microextraction (DLLME) has been developed to preconcentrate eighteen organochlorine pesticides (OCPs) from water samples prior to analysis by gas chromatography-mass spectrometry (GC-MS). The studied variables were extraction solvent type and volume, disperser solvent type and volume, aqueous sample volume and temperature. The optimum experimental conditions of the proposed DLLME method were: a mixture of 10 L tetrachloroethylene (extraction solvent) and 1 mL acetone (disperser solvent) exposed for 30 s to 10 mL of the aqueous sample at room temperature (20 • C). Centrifugation of cloudy solution was carried out at 2300 rpm for 3 min to allow phases separation. Finally, 2 L of extractant was recovered and injected into the GC-MS instrument. Under the optimum conditions, the enrichment factors ranged between 46 and 316. The calculated calibration curves gave a high-level linearity for all target analytes with correlation coefficients ranging between 0.9967 and 0.9999. The repeatability of the proposed method, expressed as relative standard deviation, varied between 5% and 15% (n = 8), and the detection limits were in the range of 1-25 ng L −1 . The LOD values obtained are able to detect these OCPs in aqueous matrices as required by EPA methods 525.2 and 625. Analysis of spiked real water samples revealed that the matrix had no effect on extraction for river, surface and tap waters; however, urban wastewater sample shown a little effect for five out of eighteen analytes.
Microchemical Journal, 2010
A simple and rapid method based on solid-phase micro extraction (SPME) technique followed by gas chromatography-mass spectrometry with selected ion monitoring (GC-MS, SIM) was developed by the simultaneous determination of 16 pesticides of seven different chemical groups [Six organophosphorus (trichlorfon, diazinon, methyl parathion, malathion, fenthion and ethyon), three pyrethroids (bifenhin, permethrin, cypermethrin), two imidazoles (imazalil and prochloraz), two strobilurins (azoxystrobin and pyraclostrobin), one carbamate (carbofuran), one tetrazine (clofentezine), and one triazole (difenoconazole)] in water. The pesticides extraction was done with direct immersion mode (DI-SPME) of the polyacrilate fiber (PA 85 µm). The extraction temperature was adjusted to 50°C during 30 min, while stirring at 250 rpm was applied. After extraction, the fiber was introduced in the GC injector for thermal desorption for 5 min. at 280°C. The method was validated using ultra pure water samples fortified with pesticides at different concentration levels and shows good linearity in the concentrations between 0.05 and 250.00 ng mL − 1 . The LOD and LOQ ranged, from 0.02 to 0.30 ng mL − 1 and 0.05 to 1.00 ng mL − 1 , respectively. Intra-day and inter-day precisions were determined in two concentration levels (5.00 and 50.00 ng mL − 1 ). Intra-day relative standard deviation (%R.S.D.) ranged between 3.6 and 13.6%, and inter-day (%R.S.D.) ranged between 6.3 and 18.5%. Relative recovery tests were carried out spiking the ultra pure sample with standards in three different concentration levels 0.20, 5.00 and 50.00 ng mL − 1 . The recovery at 0.20 ng mL − 1 level varied from 86.4 ± 9.4% to 108.5 ± 10.5%, at 5.00 ng mL − 1 level varied from 77.5 ± 10.8% to 104.6 ± 9.6% and at 50.00 ng mL − 1 level varied from 70.2 ± 4.6% to 98.4 ± 8.5%. The proposed SPME method was applied in twenty-six water samples collected in the "Platô de Neópolis", State of Sergipe, Brazil. Methyl parathion was detected in five samples with an average concentration of 0.17 ng mL − 1 and bifenthrin, pyraclostrobin and azoxystrobin residues were found in three samples with average concentrations of 2.28, 3.12 and 0.15 ng mL − 1 , respectively.
Sample preparation for GC analysis of selected pesticides in surface water
Chemosphere, 1999
A new isolation procedure for the determination of nitrogen/phosphorous containing pesticides and organochlorine pesticides in water was tested, and statistical evaluation of the recoveries was performed. The procedure, designed specifically for the analysis of semi-volatile compounds in water containing Suspended Particulate Matter (SPM), utilizes a specially designed filtration vessel coupled directly to an SPE cartridge. The studies were based on surface water samples (from the Vistula River) spiked with pesticides. SPM separation and analyte isolation/concentration were carried out in a special filtration vessel. Pesticides were sorbed both on the SPE cartridge and on the suspended matter. The cartridge and the filter with the suspended matter were extracted separately with a solvent, which enabled the determination of ana.lyte distribution between the two. For organochlorine pesticides, between 3 and 60 % of the initial amount was found on the filter, while the recoveries in the filtrate ranged from 30 to 98 %. Total recoveries of organochlorine pesticides from surface water samples spiked with pesticides using the method described were high, ranging from 90 to 101 %. The amounts of nitrogen/phosphorus containing pesticides recovered from the filter were lower than 2 %, while those f?om the filtrate ranged from 69 to 92 %. Total recoveries of nitrogen/phosphorus containing pesticides from surface water samples were high, ranging from 71 to 92 %.
Journal of Liquid Chromatography & Related Technologies, 2005
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 .
Journal of Separation Science, 2008
A new, fast, simple and environmentally friendly analytical method has been developed to determine six siloxanes in water samples: octamethyltrisiloxane, octamethylcyclotetrasiloxane, decamethyltetrasiloxane, decamethylcyclopentasiloxane, dodecamethylpentasiloxane and dodecamethylcyclohexasiloxane. The analytical method consists of magnetic solid-phase extraction employing graphene oxide/Fe 3 O 4 as sorbent for the separation and preconcentration of siloxanes prior to GC-MS determination. The extraction procedure was optimized by means of a Plackett-Burman design. Under the optimized extraction conditions (graphene oxide/Fe 3 O 4 , 20 mg; extraction time, 10 min; eluent volume, 0.5 mL ACN; elution time, 2.5 min; sample volume, 20 mL), the method rendered repeatability levels with a relative standard deviation between 9 and 20% (n=6, 10 µg L-1). Methodological limits of detection ranged from 0.003 µg L-1 to 0.1 µg L-1. The linearity of the method was studied between the methodological limit of quantification and 100 µg L-1 , obtaining correlation coefficient values between 0.990 and 0.999. The applicability of the method was assessed by analyzing drinking, river and wastewater samples. Relative recovery values ranged between 70 and 120% (1 and 60 µg L-1 spiking level) showing that the matrix had a negligible effect on extraction. Finally, the greenness of this method was confirmed by the semiquantitative Eco-Scale metrics.
ELECTROPHORESIS, 2017
An analytical methodology based on co-precipitation-assisted coacervative extraction (cop-CAE) coupled to High-Performance Liquid Chromatography (HPLC-UV) was developed for determination of five organophosphorus pesticides (OPPs), including fenitrothion, guthion, parathion, methidathion and chlorpyrifos, in water samples. It involves a green technique leading to an efficient and simple analytical methodology suitable for high throughput analysis. Relevant physicochemical variables were studied and optimized on the analytical response of each OPP. Under optimized conditions, the resulting methodology was as follows: an aliquot of 9 mL of water sample was placed into a centrifuge tube and 0.5 mL sodium citrate 0.1 M, pH 4, 0.08 mL Al 2 (SO 4) 3 0.1 M and 0.7 mL SDS 0.1 M were added and homogenized. After centrifugation the supernatant was discarded. A 700 μL aliquot of the coacervate rich-phase obtained was dissolved with 300 µL of methanol and 20 µL of the resulting solution was analyzed by HPLC-UV. The resulting LODs ranged within 0.7-2.5 ng mL-1 and the achieved RSD and recovery values were < 8% (n=3) and > 81%, respectively. The proposed analytical methodology was successfully applied for the analysis of five OPPs in water samples for human consumption of different locations of Mendoza.
Journal of the Brazilian Chemical Society, 2009
Neste trabalho, um método para determinação dos agrotóxicos carbofurano, clomazona, 2,4-D e tebuconazol em águas subterrâneas é descrito. O método utiliza a Extração em Fase Sólida (EFS) com cartuchos de C18 e quantificação por Cromatografia Líquida de Alta eficiência com Detector de Arranjo de Diodos (CLAE-DAD). Após a otimização dos parâmetros de extração e separação dos compostos, o método foi validado avaliando-se curva analítica, linearidade, limites de detecção e quantificação, precisão e exatidão (recuperação). O método apresentou recuperações médias de 87,9% e 96,9%, para a repetibilidade e precisão intermediária, respectivamente, com RSD de 0,8 a 20,7% para todos os compostos. O método será empregado na determinação de agrotóxicos em águas subterrâneas com um limite de quantificação de 0,2 µg L-1. A method is described for the determination of the pesticides carbofuran, clomazone, 2,4-D and tebuconazole in groundwaters. The method involves solid phase extraction (SPE) with C18 cartridges and quantification by high performance liquid chromatography with diode array detector (HPLC-DAD). After the optimization of the extraction and separation parameters, the method was validated by evaluating the analytical curve, linearity, limits of detection and quantification, precision and accuracy (recovery). The method presents an average recovery of 87.9% and 96.9%, in repeatability and intermediate precision conditions, respectively, with adequate precision (RSD from 0.8 to 20.7%), for all compounds. The method will be applied to determine pesticides in groundwater samples with limit of quantification of 0.2 µg L-1 .
Journal of Analytical Methods in Chemistry, 2016
This paper describes a simple and quick method for sampling and also for carrying out the preconcentration of pesticides in environmental water matrices using two-phased hollow fiber liquid phase microextraction (HF-LPME). Factors such as extraction mode, time, solvents, agitation, and salt addition were investigated in order to validate the LPME method. The following conditions were selected: 6 cm of polypropylene hollow fiber, ethyl octanoate as an acceptor phase, and extraction during 30 min under stirring at 200 rpm. The optimized method showed good linearity in the range of 0.14 to 200.00 μg L−1; the determination coefficient (R2) was in the range of 0.9807–0.9990. The LOD ranged from 0.04 μg L−1to 0.44 μg L−1, and LOQ ranged from 0.14 μg L−1to 1.69 μg L−1. The recovery ranged from 85.17% to 114.73%. The method was applied to the analyses of pesticides in three environmental water samples (a spring and few streams) collected in a rural area from the state of Minas Gerais, Brazil.
Analytica Chimica Acta, 2009
A rapid and simple dispersive liquid-liquid microextraction (DLLME) has been developed to preconcentrate eighteen organochlorine pesticides (OCPs) from water samples prior to analysis by gas chromatography-mass spectrometry (GC-MS). The studied variables were extraction solvent type and volume, disperser solvent type and volume, aqueous sample volume and temperature. The optimum experimental conditions of the proposed DLLME method were: a mixture of 10 L tetrachloroethylene (extraction solvent) and 1 mL acetone (disperser solvent) exposed for 30 s to 10 mL of the aqueous sample at room temperature (20 • C). Centrifugation of cloudy solution was carried out at 2300 rpm for 3 min to allow phases separation. Finally, 2 L of extractant was recovered and injected into the GC-MS instrument. Under the optimum conditions, the enrichment factors ranged between 46 and 316. The calculated calibration curves gave a high-level linearity for all target analytes with correlation coefficients ranging between 0.9967 and 0.9999. The repeatability of the proposed method, expressed as relative standard deviation, varied between 5% and 15% (n = 8), and the detection limits were in the range of 1-25 ng L −1 . The LOD values obtained are able to detect these OCPs in aqueous matrices as required by EPA methods 525.2 and 625. Analysis of spiked real water samples revealed that the matrix had no effect on extraction for river, surface and tap waters; however, urban wastewater sample shown a little effect for five out of eighteen analytes.