Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PESTICIDES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,549 records · Page 86Linked to original sources
PubMed2004

Rapid multiresidue extraction method of organochlorinated pesticides from fish feed.

A rapid multiresidue extraction method for organochlorinated pesticides from fish feed was developed, which is based on the extracted fat treatment by n-hexane, concentrated sulphuric acid and ENVI-carb, a graphitized non-porous carbon material. The final residue, obtained in about 50 min, was dissolved in isooctane and analysed by gas chromatography with an electron capture detector (GC/ECD). The presence of the extracted pesticides was confirmed by gas chromatography-mass spectrometry (GC/MS). Concentration of sulphuric acid and amount of ENVI-carb were optimized in order to improve analytes recovery, accuracy and detection limits. This simple and relatively fast method allowed a high recovery of the HCB, Lindane, HEPO, p,p'-DDE, p,p'-DDD, p,p'-DDT residues, with mean values in the range 68-124% at four fortification levels (12.5, 25.0, 50.0, 100.0 ng/g), and coefficients of variation between 1.9 and 20.2%. Detection limit were equal to 3.0 ng/g, related to fat, for all pesticides, and calibration curves were linear (r > 0.999) in the range of explored concentrations from the detection limit to 100 ng/g. For all pesticides a good repeatability was obtained (CV% values in the range 0.23-4.16%) when a sequence of six injections of the isooctane extraction solution was performed. The usefulness of the proposed method has been tested by the analysis of fish feed samples.

Animal Feed↗
PubMed2004

Determination of pesticides in soil by liquid-phase microextraction and gas chromatography-mass spectrometry.

Trace amounts of pesticides in soil were determined by liquid-phase microextraction (LPME) coupled to gas chromatography-mass spectrometry (GC-MS). The technique involved the use of a small amount (3 microl) of organic solvent impregnated in a hollow fiber membrane, which was attached to the needle of a conventional GC syringe. The organic solvent was repeatedly discharged into and withdrawn from the porous polypropylene hollow fiber by a syringe pump, with the pesticides being extracted from a 4 ml aqueous soil sample into the organic solvent within the hollow fiber. Aspects of the developed procedure such as organic solvent selection, extraction time, movement pattern of plunger, concentrations of humic acid and salt, and the proportion of organic solvent in the soil sample, were optimized. Limits of detection (LOD) were between 0.05 and 0.1 microg/g with GC-MS analysis under selected-ion monitoring (SIM). Also, this method provided good precision ranging from 6 to 13%; the relative standard deviations were lower than 10% for most target pesticides (at spiked levels of 0.5 microg/g in aqueous soil sample). Finally, the results were compared to those achieved using solid-phase microextraction (SPME). The results demonstrated that LPME was a fast (within 4 min) and accurate method to determine trace amounts of pesticides in soil.

Gas Chromatography-Mass Spectrometry↗
PubMed2004

Multiple-stage mass spectrometric analysis of six pesticides in oranges by liquid chromatography-atmospheric pressure chemical ionization-ion trap mass spectrometry.

Six pesticides were determined by liquid chromatography (LC) with positive ion (PI) atmospheric pressure chemical ionization quadrupole ion-trap tandem mass spectrometry (APCI-MS-MS). Ion fragmentation was studied by MS, MS2 and MS3. Fragmentation of the pesticides produced ions formed by various losses from the side-chains and through heterocyclic ring opening, but without any common fragmentation pathway. Multiple reaction monitoring (MRM) of MS, MS2 and MS3 was used to identify and quantify the pesticides. The samples were extracted with ethyl acetate and dried over anhydrous sodium sulfate. Comparison of the three MS modes showed that MS3 is slightly less sensitive but much more selective. Recoveries from oranges were 72-94% at the limit of quantification (LOQ) level for all MS modes. The LOQs were 0.001-0.3 mg kg(-1) quantifying by means of the MS3 product ion. The method was used to analyse a number of orange samples. This is the first report on using MS3 product ions for quantification of pesticide residues.

Atmospheric Pressure↗
PubMed2005

High-performance liquid chromatographic determination of pesticides in tomatoes using laboratory-made NH2 and C18 solid-phase extraction materials.

A method for high-performance liquid chromatographic (HPLC) multiresidue determination of six pesticides in tomatoes was developed and validated. Silica-based C18 (octadecyl) and NH2 (aminopropyl) solid-phase extraction (SPE) sorbents, made in our laboratory, were used for sample preparation. The SPE materials were obtained by thermal immobilization of appropriate polysiloxanes onto 40 microm silica surfaces and were used in sample preparation for multiresidue analysis of the following pesticides: tebuthiuron and diuron (urea herbicides), simazine, atrazine and ametryn (triazines herbicides) and benomyl (benzimidazol fungicide). The results were compared with similar commercial materials. Reversed-phase high-performance liquid chromatography (RP-HPLC) using a Purospher RP-18 5 microm column and ACN: 0.01% aqueous NH4OH, pH 8.4 (35:65, v/v) as mobile phase, at 0.7 mlmin(-1), with 235 nm UV detection, was used for separation and quantification of the pesticides. Method validation was performed at three fortification levels (100, 200, 1000 microg l(-1)). Limits of detection and quantification show that the methods developed can be used to detect the pesticides in concentrations below the maximum residue levels (MRL) established by the Codex Alimentarius, USA, European Union and Brazilian legislations. The results showed that aminopropyl materials have a better performance than the octadecyl sorbents. Laboratory-made materials give results similar to commercial sorbents, with recoveries and precisions in agreement with directives for method validation in residue analysis.

Chromatography, High Pressure Liquid↗
PubMed2005

Search on ruggedness of fast gas chromatography-mass spectrometry in pesticide residues analysis.

In this study, suitability of fast gas chromatography-mass spectrometry (GC-MS) on a narrow-bore column with a programmed temperature vaporizer for the analysis of pesticide residues in non-fatty food was evaluated. The main objectives were ruggedness and stability of chromatographic system with regards to co-extractives injected. The chromatographic matrix induced response enhancement was found to be strongly dependent on the concentration of residues and is reaching up to 700% compared to the pesticides solutions in a neat solvent. However, the responses of pesticides in matrix-matched standards at different concentration levels do not significantly change during 130 injections. Response enhancement/or decrease is influenced by the sample preparation technique. External calibration with matrix-matched calibration standards should, therefore, provide results with good precision also at the concentration level of 0.005 mg kg(-1). Special attention is given to the performance of the chromatographic column and retention gap with regards to peak widths, peak tailing and different sample preparation methods. During approximately 460 matrix sample injections, the performance of the analytical column was acceptable. GC-MS set-up with 0.15 mm i.d. column can be successfully utilized for the pesticide residues analysis.

Food Analysis↗
PubMed2005

Modelling bioconcentration of pesticides in fish using biopartitioning micellar chromatography.

Ecotoxicity assessment is essential before placing new chemical substances on the market. An investigation of the use of the chromatographic retention (log k) in biopartitioning micellar chromatography (BMC) as an in vitro approach to evaluate the bioconcentration factor (BCF) of pesticides in fish is proposed. A heterogeneous set of 85 pesticides from six chemical families was used. For pesticides exhibiting bioconcentration in fish (experimental log BCF > 2), a quantitative retention-activity relationships (QRAR) model is able to perform precise log BCF estimations of new pesticides. Considering the present data, the results based on log k seem to be more reliable than those from available software (BCFWIN and KOWWIN) and from log P (quantitative structure-activity relationships (QSAR)). It is also possible to perform risk assessment tasks fixing a threshold value for log k, which substitute two common threshold values, log P and experimental log BCF, avoiding the experimental problems related with these two parameters.

Animals↗
PubMed2005

Multi-residue pesticide analysis in fruits and vegetables by liquid chromatography-time-of-flight mass spectrometry.

In this work, a new multi-residue methodology using liquid chromatography-time-of-flight mass spectrometry (LC-TOF-MS) for the quantitative (routine) analysis of 15 pesticide residues has been developed. The analytical performance of the method was evaluated for different types of fruit and vegetables: pepper, broccoli, tomato, orange, lemon, apple and melon. The accurate mass measurements were compared in different matrices at significantly different concentration levels (from 0.01 to 0.5 mg/kg) obtaining accuracy errors lower than 2 ppm, which is well within the accepted limits for elemental confirmation. Linearity of response over two orders of magnitude was demonstrated (r > 0.99). Matrix effects resulting in suppression or enhancement of the response were frequently observed, most notably in broccoli and citrus. Instrumental limits of detection (LOD) were between 0.0005 and 0.03 mg/kg depending on the commodity and pesticide studied, all being within European Union regulations for food monitoring program. Finally, the methodology was applied to the analysis of two samples from an inter-laboratory exercise. The high degree of confirmation for target pesticides by accurate mass measurements demonstrated the applicability of the method in routine analysis. This study is a valuable indicator of the potential of LC-TOF-MS for quantitative multi-residue analysis of pesticides in vegetables and fruits.

Chromatography, Liquid↗
PubMed2005

Selective solid-phase extraction using molecularly imprinted polymer for the analysis of polar organophosphorus pesticides in water and soil samples.

An analytical methodology for the analysis of four polar organophophorus pesticides (monocrotophos, mevinphos, phosphamidon, omethoate) in water and soil samples incorporating a molecularly imprinted solid-phase extraction (MISPE) process using a monocrotophos-imprinted polymer was developed. Binding study demonstrated that the polymer showed excellent affinity and high selectivity to monocrotophos. The MISPE procedure including the clean-up step to remove any interferences was optimized. The accuracy and selectivity of the MISPE process developed were verified using a non-imprinted (blank) polymer and a classical ENVI-18 cartridge as the SPE matrix during control experiments. The use of MISPE improved the accuracy and precision of the GC method and lowered the limit of detection. The recoveries of four polar organophosphorus pesticides (OPPs) extracted from 1 L of river water at a 100 ng/L spike level were in the range of 77.5-99.1%. The recoveries of organophosphorus pesticides extracted from a 5-g soil sample at the 100 microg/kg level were in the range of 79.3-93.5%. The limit of detection varied from 10 to 32 ng/L in water and from 12 to 34 microg/kg in soil samples. The molecularly imprinted polymer (MIP) enabled the selective extraction of four organophosphorus pesticides successfully from water and soil samples, demonstrating the potential of molecularly imprinted solid-phase extraction for rapid, selective, and cost-effective sample pretreatment.

Chromatography, Gas↗
PubMed2005

Fully automated online solid phase extraction coupled directly to liquid chromatography-tandem mass spectrometry. Quantification of sulfonamide antibiotics, neutral and acidic pesticides at low concentrations in surface waters.

A fully automated online solid phase extraction-liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) instrumental setup has been developed for the quantification of sulfonamide antibiotics and pesticides in natural water. The direct coupling of an online solid phase extraction cartridge (Oasis HLB) to LC-MS/MS was accomplished using column switching techniques. High sensitivity in the low ng/L range was achieved by large volume injections of 18 mL with a combination of a tri-directional auto-sampler and a dispenser system. This setup allowed high sample throughput with a minimum of investment costs. Special emphasis was placed on low cross contamination. The chosen approach is suitable for research as well as for monitoring applications. The flexible instrumental setup was successfully optimised for different important groups of bioactive chemicals resulting in three trace analytical methods for quantification of (i) sulfonamide antibiotics and their acetyl metabolites; (ii) neutral pesticides (triazines, phenylureas, amides, chloracetanilides) and (iii) acidic pesticides (phenoxyacetic acids and triketones). Absolute extraction recoveries from 85 to 112% were obtained for the different analytes. More than 500 samples could be analyzed with one extraction cartridge. The inter-day precision of the method was excellent indicated by relative standard deviations between 1 and 6%. High accuracy was achieved by the developed methods resulting in maximum deviation relative to the spiked amount of 8-15% for the different analytes. Detection limits for various environmental samples were between 0.5 and 5 ng/L. Matrix induced ion suppression was in general smaller than 25%. The performance of the online methods was demonstrated with measurements of concentration dynamics of sulfonamide antibiotics and pesticides concentrations in a little creek during rain fall events.

Anti-Bacterial Agents↗
PubMed2005

Determination of the limits of identification and quantitation of selected organochlorine and organophosphorous pesticide residues in surface water by full-scan gas chromatography/mass spectrometry.

In this work, we report a reliable method for quantitation and determination of the limits of identification of 14 organochlorine and organophosphorous pesticide (OPP) residues in surface water. The method features the simultaneous identification and quantitation of targeted pesticides and the possibility of identification of any other eluting compounds. The method is based on liquid-liquid extraction (LLE) with a mixture of petroleum ether and dichloromethane (70:30, v/v) followed by gas chromatographic separation and a full-scan mass spectrometric detection (GC-MS). The method presents a new validation parameter, limit of identification (LOI) which is defined for our purpose as the lowest analyte concentration that yields a library searchable mass spectrum. The method is linear over the range 0.048-1.20microgL(-1) for nine pesticides and 0.024-0.60microgL(-1) for the other five pesticides. Correlation coefficients vary between 0.988 and 0.998. Limits of detection (LODs) vary between 0.005 and 0.05microgL(-1) for 4,4'-DDT and LOIs vary between 0.012 and 0.048microgL(-1).

Alkanes↗
PubMed2005

Response surface optimization for determination of pesticide multiresidues by matrix solid-phase dispersion and gas chromatography.

An optimized multiresidue analysis method based on matrix solid-phase dispersion (MSPD) and gas chromatography (GC) is proposed for the determination of organochlorines and pyrethroids in the tea samples. Response surface methodology (RSM) was used to optimize the extraction conditions of MSPD, such as the sorbent type, eluent composition, dichloromethane concentration and eluting volume. Desirability function approach was employed to optimize the pesticide recoveries and matrix cleanup. Compromising the recoveries and cleanup degree, MSPD was carried out with Florisil as the sorbent and n-hexane-dichloromethane (1:1, v/v) as the eluent. The pesticide recoveries in tea samples were better than 80% spiked in the concentration range of 0.01-0.05mg/kg and the relative standard deviations were lower than 7%. The quantification limits of the pesticides were in the range of 0.002-0.06mg/kg, which were lower than the maximum residue limits of the pesticides in tea samples established by the European Union.

Chromatography, Gas↗
PubMed2005

Simultaneous determination of carbamate and organophosphorus pesticides in fruits and vegetables by liquid chromatography-mass spectrometry.

A liquid chromatography-mass spectrometry (LC-MS) method was established for the purpose of simultaneous determination of carbamate and organophosphorus (OPPs) pesticides in fruits and vegetables. Samples were extracted with acetonitrile; and then prepared by dispersive solid-phase extraction (dispersive-SPE) with primary secondary amine (PSA) as the sorbent. Four common representative samples (tomato, apple, carrot, and cabbage) were selected from the supermarket to investigate the effect of different matrices on pesticides recoveries and assay precision after spiking samples with 0.05 mg/kg. Matrix composition did not interfere significantly with the determination of the pesticides. The obtained recoveries were, with a few exceptions, in the range of 70-110% with RSDs less than 8%. It was applied to pesticide residue monitoring in vegetables and fruits from local markets.

Carbamates↗
PubMed2006

Comparison of ultra-performance liquid chromatography and high-performance liquid chromatography for the determination of priority pesticides in baby foods by tandem quadrupole mass spectrometry.

Determination of 16 priority pesticides and transformation products specified in the EU Baby Food Directive 2003/13/EC has been compared using high-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography (UPLC) coupled to tandem quadrupole mass spectrometry (MS/MS). Prior to analysis, co-extractives were removed from acetonitrile extracts using dispersive solid-phase extraction (SPE) with primary secondary amine (50 mg). Extracts spiked with pesticides at 1 microg kg(-1) yielded average recoveries in the range 85-119%, with relative standard deviations less than 17%. The HPLC-MS/MS and UPLC-MS/MS multi-residue methods developed are simple, rapid and suitable for the quantification and confirmation of the 16 priority pesticides in fruit-, potato- and cereal-based baby food at 1 microg kg(-1). The major advantages of UPLC, using 1.7 microm particles, over HPLC are the speed of analysis, the narrower peaks (giving increased signal-to-noise ratio) and improved confirmation for the targeted pesticides in the analyses of baby foods.

Chromatography, High Pressure Liquid↗
PubMed2006

Simultaneous multidetermination of residues of pesticides and polycyclic aromatic hydrocarbons in olive and olive-pomace oils by gas chromatography/tandem mass spectrometry.

A multiresidue method for determining major pesticides and polycyclic aromatic hydrocarbons (PAHs) in olive oils in a single injection by use of gas chromatography/tandem mass spectrometry (GC-MS/MS) is proposed. Samples are previously extracted with an acetonitrile/n-hexane mixture and cleaned up by gel permeation chromatography. Electron ionization and chemical ionization allow pesticides and PAHs to be determined in a single analysis. The precision obtained was quite satisfactory (relative standard deviations ranged from 3 to 7.8%), and so were recoveries (84-110%). The linear relation was observed from 1 to 500 microg/kg for pesticides and 0.3 to 200 microg/kg for PAHs; also, the determination coefficient, R(2), was better than 0.995 in all instances. The proposed method was applied to the routine analysis of PAH and pesticide residues in virgin and refined olive oil and olive-pomace oil samples.

Chromatography, Gel↗
PubMed2006

Application of a single-drop microextraction for the analysis of organophosphorus pesticides in juice.

In this study, a new method for the determination of organophosphorus pesticides (OPPs) (ethoprophos, diazinon, parathion methyl, fenitrothion, malathion, isocarbophos and quinaphos) in orange juice was developed. Single-drop microextraction (SDME) parameters, such as organic solvent, drop volume, agitation rate, extraction time, and salt concentration were optimized through analysis of OPPs in fortified water. The orange juice was simply centrifuged and diluted with water, extracted by SDME and analyzed by gas chromatography (GC) equipped with a flame photometric detection (FPD). Fortification tests were conducted for concentrations between 10 and 500 microg/L; mean relative recoveries for each pesticide were all above 76.2% and below 108.0%. Limits of detection of the method for orange juice were below 5 microg/L for all target pesticides. The repeatability of the proposed method, expressed as relative standard deviation varied between 4.6 and 14.1% (n=5). The proposed method is acceptable in the analysis of OPPs pesticides in juice matrices.

Chromatography, Gas↗
PubMed2006

Poly(methyloctylsiloxane) immobilized on silica as a sorbent for solid-phase extraction of some pesticides.

A laboratory-made sorbent for solid-phase extraction (SPE) was obtained by thermal immobilization of poly(methyloctylsiloxane) (PMOS) onto silica. Cartridges packed with the new sorbent were used for the simultaneous determination of imazethapyr, nicosulfuron, diuron, linuron and chlorimuron-ethyl in water. These pesticides were separated and quantified using high-performance liquid chromatography with diode array detection (HPLC-DAD). The recoveries achieved with the laboratory-made PMOS cartridges were compared with those of some commercially available silica-based and polymer-based cartridges having C18, C8 and NH(2) pendant groups. Method validation using the laboratory-made sorbent was performed for the five pesticides at three fortifications levels (1x, 2x and 10x the limit of quantification of each pesticide). The laboratory-made PMOS cartridge has low cost preparation and showed good recoveries (72-111%) for all pesticides. Repeatability and intermediate precision were lower than 15%. Its performance was similar or even better, in some cases, than those of the commercial cartridges.

Chemical Fractionation↗
PubMed2006

Fast screening of pesticide multiresidues in aqueous samples by dual stir bar sorptive extraction-thermal desorption-low thermal mass gas chromatography-mass spectrometry.

A method for fast screening of pesticide multiresidues in aqueous samples using dual stir bar sorptive extraction-thermal desorption-low thermal mass gas chromatography-mass spectrometry (dual SBSE-TD-LTM-GC-MS) has been developed. Recovery of 82 pesticides - organochlorine, carbamate, organophosphorous, pyrethroid and others - for the SBSE was evaluated as a function of octanol-water distribution coefficients (log K(o/w): 1.7-8.35), sample volume (2-20 mL), salt addition (0-30% NaCl), and methanol addition (0-20%). The optimized method consists of a dual SBSE performed simultaneously on respectively a 20-mL sample containing 30% NaCl and a 20-mL sample without modifier (100% sample solution). One extraction with 30% NaCl is mainly targeting solutes with low K(o/w) (log K(o/w)<3.5) and another extraction with unmodified sample solution is targeting solutes with medium and high K(o/w) (log K(o/w)>3.5). After extraction, the two stir bars are placed in a single glass desorption liner and are simultaneously desorbed. The desorbed compounds are analyzed by use of LTM-GC-MS with fast temperature programming (75 degrees C min(-1)) using a 0.18 mm i.d. narrow-bore capillary column and fast scanning (10.83 scan s(-1)) using quadrupole MS. The method showed good linearity (r(2)>0.9900) and high sensitivity (limit of detection: <10 ng L(-1)) for most of the target pesticides. The method was applied to the determination of pesticides at nanograms per liter levels in river water and brewed green tea.

Beverages↗
PubMed2006

Determination of pesticides in wine using micellar electrokinetic chromatography with UV detection and sample stacking.

In this work, the analysis of a group of four fungicides (pyrimethanil, nuarimol, procymidone and cyprodinil) and one insecticide (pirimicarb) by micellar electrokinetic chromatography (MEKC) with UV detection using the on-line preconcentration strategy called reversed electrode polarity stacking mode (REPSM) is proposed. After optimisation, an adequate separation electrolyte for the separation and stacking of these pesticides was obtained which consisted of 100 mM borate, 60 mM sodium dodecyl sulphate (SDS), at pH 9.0 and 2% 2-propanol. The use of this running buffer together with the REPSM preconcentration method provided limits of detection (LODs) between 38.3 and 241 microg/L. In order to apply the developed methodology for the analysis of these pesticides in wine samples, several off-line preconcentration strategies (mainly, solid-phase extraction, SPE, and solid-phase microextraction, SPME) were tested. Although the use of a SPE procedure, optimized in this work for water samples, using Oasis HLB cartridges, provided mean recovery values between 79 and 100% for spiked water samples, it could not be applied to the extraction of these pesticides from wine samples due to high interference from the sample matrix. However, the use of a SPME procedure using polydimethylsiloxane/divynilbenzene (PDMS/DVB) fibers allowed the selective extraction of four of the five pesticides which could be perfectly determined. The final combination of the off-line SPME and on-line REPSM preconcentration strategies allowed obtaining LODs between 17.6 and 32.3 microg/L.

Chromatography, Micellar Electrokinetic Capillary↗