Pesticides In Ground Research Articles

An Alternative Strategy for Screening and Confirmation of 330 Pesticides in Ground- and Surface Water Using Liquid Chromatography Tandem Mass Spectrometry.

The presence of pesticide residues in water is a huge worldwide concern. In this paper we described the development and validation of a new liquid chromatography tandem mass spectrometric (LC-MS/MS) method for both screening and quantification of pesticides in water samples. In the sample preparation stage, the samples were buffered to pH 7.0 and pre-concentrated on polymeric-based cartridges via solid-phase extraction (SPE). Highly sensitive detection was carried out with mobile phases containing only 5 mM ammonium formate (pH of 6.8) as an eluent additive and using only positive ionization mode in MS/MS instrument. Hence, only 200-fold sample enrichment was required to set a screening detection limit (SDL) and reporting limit (RL) of 10 ng/L. The confirmatory method was validated at 10 and 100 ng/L spiking levels. The apparent recoveries obtained from the matrix-matched calibration (5–500 ng/L) were within the acceptable range (60–120%), also the precision (relative standard deviation, RSD) was not higher than 20%. During the development, 480 pesticides were tested and 330 compounds fulfilled the requirements of validation. The method was successfully applied to proficiency test samples to evaluate its accuracy. Moreover, the method robustness test was carried out using higher sample volume (500 mL) followed by automated SPE enrichment. Finally, the method was used to analyze 20 real samples, in which some compounds were detected around 10 ng/L, but never exceeded the assay maximum level.

Distribution and Variation of Some Pesticides in Ground and Rural tap Water in Ausiem City, Giza, Egypt

Distribution and Variation of Some Pesticides in Ground and Rural tap Water in Ausiem City, Giza, Egypt

Assessment of Organic Pesticides in Ground and Surface Water in Bhopal India

Analytical assessment of surface and ground water samples for presence of organic pesticides is being reported in this paper. Analytical measurement was carried out for 15 samples each of surface and ground water collected from selected points near agricultural fields from river Betwa in Bhopal area. The sample size was stretched across 20sq.k.m .Pesticides were analysed by GLC and identified by comparing with standard reference compounds .Traces of Various pesticides including HCH ( α β Y isomer),Aldrin , Endosulphan were found in all samples. Pesticide content was more in surface than ground water suggesting primary entry of pesticides into river water due to run off from nearby fields. βHCH content was more than other isomers.

Multiresidue method for the simultaneous determination of four groups of pesticides in ground and drinking waters, using solid-phase microextraction–gas chromatography with electron-capture and thermionic specific detection

A common sample preparation procedure capable of efficiently concentrating various groups of pesticides, taking advantage of universal detectors like the mass spectrometer or combined techniques of group selective detectors like gas chromatography–electron capture detection (ECD)/thermionic specific detection (TSD), is desirable in environmental analysis. Six solid-phase microextraction fibres available for analysis of semi-volatiles (7, 30 and 100 μm poly(dimethylsiloxane) (PDMS), 85 μm polyacrylate, 60 μm PDMS–divinylbenzene (PDMS–DVB) and 65 μm Carbowax–DVB) were evaluated and the 60 μm PDMS–DVB was selected for the simultaneous extraction of 34 compounds, included in the organochlorine (OCPs), organophosphorous (OPPs), pyrethroid and triazine pesticide groups. All parameters affecting the extraction efficiency from water samples, namely fibre coating, sample agitation, pH and ionic strength, extraction temperature and time, were optimised. The analytical procedure involves solid-phase microextraction extraction, gas chromatographic separation and subsequent ECD and TSD via a post-column splitter adjusted to a split ratio of 1:10, respectively. Detection limits in the range of 1–10 ng l −1 for OCPs, 1–30 ng l −1 for OPPs, 20–30 ng l −1 for pyrethroids and 8–50 ng l −1 for triazines are easily attainable with the optimised procedure. The method validated for ground and drinking waters has low cost of implementation and operation although it requires careful maintenance.

Quantification of Phenylurea Pesticides by HPLC/ECD and Photolysis

Phenylurea pesticides were quantified in the picomole range using electrochemical detection after reversed-phase liquid chromatographic separation. Hydrodynamic voltammograms were recorded to determine the optimum working potential; to this end 50 ng of the pesticide solution was injected into the HPLC system while the potential of the working electrode was scaled down from +1.3 V to +0.5 V. As the electroactivity of substances may be influenced significantly by irradiation with UV light, hydrodynamic measurements were carried out with and without photolysis. In the case of fenuron and neburon the signal intensity was reduced under photolytic conditions, whereas the acitivity of chlorotoluron and linuron remained constant. However, amperometric detection is possible at a working potential 0.5 V lower than without photolysis. To explain the respective reaction mechanism under photolysis, 1H-NMR studies were performed on the example of fenuron. To obtain efficient preconcentration of water samples a C18 solid-phase extraction system was applied, this resulted in good reproducibility and high recoveries. LOD's of the method developed are in the lower picomole range and meet the requirements of the European Community Drinking Water Directive concerning the limits for pesticides in ground and drinking water. Furthermore, this method has the advantages of being rapid, simple, highly selective and sensitive.

Quantitation of chlorophenoxy acid herbicides by high-performance liquid chromatography with coulometric detection

Chlorophenoxy acids are toxic compounds used as selective herbicides in agriculture. To meet the need to determine trace levels of such pesticides in ground and drinking water, a highly selective and sensitive method using HPLC in combination with electrochemical detection has been developed. The four phenoxy acids 4-chloro-2-methylphenoxyacetic acid (MCPA), 4-(4-chloro-2-methylophenoxy)butyric acid (MCPB), 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) were investigated coulometrically in the oxidative mode. To determine the optimum working potential, hydrodynamic voltammograms were recorded at potentials between +0.1 and +1.0 V. As electrochemical activity is present only at higher potentials, the influence of photolysis was investigated with a view toward improving selectivity and sensitivity. After photoconversion by UV irradiation, detection ensued at potentials 0.3 V lower than without photolysis. For efficient preconcentration prior to HPLC-electrochemical detection, a solid-phase extraction system with C 18 cartridges was employed, resulting in high recovery and good reproducibility. The method developed meets the requirements with regard to the limits for pesticides in ground and drinking water and may be useful for the analysis of environmental herbicide residues.

Improvements in the determination of organophosphorus pesticides in ground- and wastewater samples from interlaboratory studies by automated on-line liquid-solid extraction followed by liquid chromatography-diode array detection

On-line liquid-solid extraction coupled to liquid chromatography and diode array detection (LSE-LC-DAD) was validated by participating in interlaboratory calibration studies organized by Aquacheck (Medmenham, UK). The quantitation of 11 organophosphorus pesticides ground- and wastewater samples at levels varying from 30 to 600 ng/l respectively was carried out. The solution containing the organophosphorus pesticides and the water sample was provided by Aquacheck. Between 90 and 150 ml of wastewater and ground respectively were percolated through the Prospekt C 18 precolumns (Spark Holland). The average error in comparison to the certified values from Aquacheck varied from 4 to 65%. The main problems encountered in the determination of these pesticides were the low UV absorbance of dichlorvos, mevinphos and malathion, the early breakthrough of dichlorvos and mevinphos and matrix interferences, specially abundant in the wastewater samples. In this type of water samples, the spiked level was one order of magnitude higher than in groundwater, but the error percentage was higher due to the matrix. One of the main advantages of this technique is that it permits the identification of two isomers of mevinphos, contrary to the rest of the participants who only reported trans-mevinphos. Moreover, by percolating 150 ml of water, limits of detection (LODs) below 0.1 μg/l are attained. The system behaved linearly over a concentration range of 0.4 to 5 ng/ml with 150 ml of water preconcentrated.

Determination of organophosphorus and triazine pesticides in ground- and drinking water by solid-phase extraction and gas chromatography with nitrogen-phosphorus or mass spectrometric detection

Trace enrichement and determination of ethoprophos, fenamiphos, fenthion, isophenphos, mevinphos, monocrotophos, atrazine and simazine were performed by solid-phase extraction on XAD-2 columns and Sep-Pak C 18 cartridges, subsequent elution with an organic solvent and determination by GC with nitrogen-phosphorus detection (NPD) and mass spectrometry in the selected-ion monitoring mode (MS-SIM). Ground- and drinking water volumes of 1–2.5 1 at concentrations levels of 0.1–5 μg/1 were used for application of the method. Both adsorbents provided recoveries of 75–95%. The limits of detection were 0.08–0.60 μg/1 with NPD and 0.03–0.13 μg/1 with MS-SIM.