Solid-phase extraction of pesticide residues from ground water: comparison between extraction cartridges and extraction discs (original) (raw)
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Solid-Phase Extraction of Organochlorine Pesticides from Water Samples
International Journal of Environmental Analytical Chemistry, 1990
Due to the uncensored use of pesticides in the agricultural regions of Lebanon, the contamination risks of drinking water by organic residues increase periodically in planting seasons. No previous work have been considered in North Lebanon plain concerning pesticide pollution though it is the second agricultural zone in Lebanon with an excessive activity. In this context, the aim of this study was to evaluate the contamination and to map the pollution level of groundwater by organochlorine pesticides in Northern Lebanon. Solid-phase extraction (SPE) cartridge embedded with Hydrophilic-lipophilic-balanced (HLB) copolymer were used for the isolation and trace enrichment of pesticide from water samples followed by gas chromatography coupled with mass spectrometry (GC/MS) to quantify pesticide concentrations. The levels of organochlorine pesticide recorded in groundwater of Akkar district exceeded the limits set by the Stockholm Convention on persistent organic pollutants with total amounts that can reach 14.2 µg/L. Contamination was also found to be more important inland with the frequent presence of banned pesticide such HCH isomers, 4,4'-DDT, aldrin and endrin. Appropriate remedial measures and systematic investigation of Organochlorine residues in water resources of the AKKAR district are necessary to check further aggravation of the situation.
Journal of Agricultural and Food Chemistry, 1996
A comparative study is made of the application of liquid-liquid (LLE) and liquid-solid (LSE) extraction techniques with a new sorbent with trifunctional bonding chemistry (tC 18) for environmental sampling and trace enrichment. The experimental conditions of the LLE and LSE methods were evaluated for the determination of 22 organochlorine and 2 organophosphorus pesticides, 2 triazines, and 7 polychlorinated biphenyls (PCBs), which were analyzed by gas chromatography with a capillary column and electron-capture detector (ECD). Mean recovery yields were found to be higher with the LLE method, although LSE for most of the 33 analytes assayed surpassed 70%. The detection limits for both techniques were lower than 5 ng L-1 , except for the pesticides parathion (7 ng L-1), methoxychlor (8 ng L-1), atrazine (35 ng L-1), and simazine (95 ng L-1). The absolute standard deviations and the variation coefficients of both techniques were slightly higher in LSE and ranged from 0.5 to 2.6 ng L-1 and 7 to 24%, respectively. The method was applied to the analysis of raw and finished drinking water from four towns with different water sources and qualities.
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.
Talanta, 2010
An analytical method using solid phase extraction (SPE) and analysis by gas chromatography/mass spectrometry (GC-MS) was developed to determine trace levels of a variety of 41 agricultural pesticides and selected transformation products in high-elevation surface waters. Large-volume water sampling (up to 100 L) was employed because it was anticipated that pesticide contamination, if present, would be at very low levels. The target compounds comprise pesticides (and selected oxygen transformation products) known to have been extensively used in agriculture in the San Joaquin Valley, CA, USA. Solid phase extraction using the polymeric resin Abselut Nexus was optimized to extract the pesticide analytes from water samples. A single determinative method using GC-MS with electron ionization was used for all the analytes. Recoveries from 100 L of reagent water at 100 pg/L and 1 ng/L concentrations were generally greater than 75%, although dimethoate, disulfoton, and phorate were not recovered. Analysis of the extracts without cleanup yielded detection limits for the remaining 38 analytes between 0.1 and 30 ng/L. A silica cleanup with separate analysis of 3 eluant fractions improved detection limits for 37 of the compounds to between 6 and 600 pg/L in high-elevation surface waters.
Troubleshooting in the trace analysis of organochlorine pesticides in water samples
Chromatographia, 2001
As a consequence of the high toxicity of organochlorine pesticides their presence in water for human consumption is limited by legislation. To determine these compounds at trace levels, an extraction procedure and a highly sensitive analytical technique is necessary. In this workwe have used laminar disks for the solid-phase extraction of 21 organochlorine pesticides from water. The analytical technique selected is gas chromatography with electron-capture detection. A solid-phase extraction procedure is proposed, and some problems has been encountered. Low recovery of some pesticides has been obtained, because of their adsorption by the walls of containers. To prevent this adsorption, addition of 20% methanol before the sampling step is proposed. Adsorption of pesticides by the organic matter present in water samples was also observed. Pesticides can be adsorbed by the membrane filters usually used to remove suspended particulate matter from water samples. Different kinds of filters have been tested, and the occurrence of the problem has been confirmed. The use of laminar disks in this work has overcome this problem.
Jurnal Teknologi, 2013
A new sol–gel hybrid silica–based sorbent, methyltrimethoxysilane–cyanopropyltriethoxysilane (MTMOS–CNPrTEOS) produced in our laboratory was used for highly selective and simultaneous solid phase extraction (SPE) of two polar organophosphorus pesticides (OPPs) and four non–polar OPPs from water samples. The two polar OPPs used as test analytes are dicrotophos and methamidophos while the four non–polar OPPs are diazinon, malathion, methidathion, and chlorpyrifos. Analysis of OPPs was performed using gas chromatography–mass spectrometry in scan mode. Extraction efficiency (based on peak area response) of the new sol–gel hybrid MTMOS–CNPrTEOS was superior to commercial C18 SPE sorbent. The new sorbent showed higher selectivity towards the polar dicrotophos and methamidophos and it was also able to simultaneously extract the four non–polar OPPs with higher extraction efficiency. The limit of detection at S/N=3 for the new sol–gel hybrid sorbent is 5–9× lower and similar accuracy for the...
International Journal of Environmental Analytical Chemistry, 2008
A multi-residue procedure was developed for analysis of four common pesticides in water using solid-phase extraction and high-performance liquid chromatography in combination with UV detection at 230 nm. The investigated pesticides (atrazine, dicloran, metazachlor and simazine) are highly leachable and easily migrate within the soil. Multi-walled carbon nanotubes (MWCNTs) adsorbent outperformed C 18 bonded silica and graphitized carbon black for preconcentration of the pesticides from solution. The optimum experimental conditions for pesticides extraction were carefully studied and optimised. At the optimum preconcentration conditions (sample volume: 700 mL; adsorbent mass: 300 mg; solution pH: 5.0; flow rate: 3.0 mL min À1 ; and elution medium: methanol), a quantitiative recovery for pesticides was reported and a high preconcentration factor (1400) was attained. The detection limits of the proposed method were found in the range: 5-15 ng L À1. The dynamic range for simazine and atrazine determination was extended from 15 to 1000 ng L À1 , while for metazachlor and dicloran the range was within 60-1000 ng L À1. Five replicate determinations of 70 ng of pesticides mixture present in 700 mL solution gave good results with RSD values within the range 2.5 to 4.6%. The present method gave recoveries from 92.7 to 95.3% for determination of 100 ngL À1 of pesticides in tap water and recoveries from 85.3 to 87.0 in well water with satisfactory RSD values (6%).
Pressurized Liquid Extraction of Organochlorine Pesticides from Certified Solid Materials
Journal of Chromatographic Science, 2007
In order to propose a versatile method to use in laboratories devoted to environmental analysis, a scheme for the determination of organochlorine pesticides from different solid matrices is evaluated. Pressurized liquid extraction is chosen as the sample preparation technique, followed by the purification of the extract by means of solid-phase extraction with Envi-carb cartridge (100 m 2 /g). Finally, the extracts are analyzed by programmed temperature vaporization (PTV)-gas chromatography (GC)-electron-capture detection and PTV-GC-mass spectrometry. The suitability of the method for the analysis of different matrices is determined by the extraction and analysis of four certified reference materials of solid matrices: CRM 804-050 (soil), SRM 1941b (organics in marine sediment), SRM 1944 (New York/New Jersey waterway sediment) and SRM 1649a (Urban Dust). Good statistical concordance between the results obtained and the certified or reference concentration are observed for most of the analyzed pesticides.