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PubMed1991

The flavin-containing monooxygenase of mouse kidney. A comparison with the liver enzyme.

Flavin-containing monooxygenase (FMO; EC 1.14.13.8) was purified from mouse kidney microsomes and compared to that isolated from mouse liver microsomes. The purified enzymes from kidney and liver appeared as a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with an apparent molecular weight of 58,000 daltons. On wide range (pH 3.5 to 9.0) isoelectric focusing, FMOs from kidney and liver resolved as a single band with an isoelectric point of 8.2. The enzymes from both kidney and liver have a pH optimum of 9.2. Thiobenzamide-S-oxidation catalyzed by both enzymes was sensitive to inhibition by the competitive inhibitors thiourea and methimazole. At an n-octylamine concentration of 3 mM, thiobenzamide-S-oxidation by the kidney FMO was increased by 122% and that by the liver FMO by 148%. Km and Vmax values were determined and compared between the two tissue enzymes for xenobiotic substrates containing nucleophilic nitrogen, sulfur or phosphorus atoms. In general, for most FMO substrates, Km and Vmax values were similar between kidney and liver FMO with only a few exceptions. The Km and Vmax values for fenthion for kidney were only half of those observed for liver FMO. Fonofos was unusual in having a low Km as well as a low Vmax for both tissue enzymes. Anti-sera developed to the FMO purified from kidney and liver showed cross-reactivity with each purified enzyme as well as with a protein with the same molecular weight as the purified FMO present in both kidney and liver microsomes. These bands showed equal intensity based on an equivalent amount of protein. Analysis of kidney and liver FMO by proteolytic digestion followed by visualization of peptides by silver staining or immunoblotting showed only minor differences between the enzymes of the two tissues. The amino acid composition of both mouse kidney and liver FMO was low in methionine and histidine and rich in aspartate/asparagine, glutamate/glutamine, leucine, valine and glycine. Edman degradation of the purified mouse kidney and liver FMO provided a single amino acid sequence of the NH2-terminus. This sequence matched exactly with the cDNA-deduced sequence reported for the pig and rabbit liver beginning with the fifth amino acid and contained the highly conserved FAD-binding domain Gly-X-Gly-X-X-Gly, commonly found in a number of other FAD-binding proteins. These studies indicate that the renal and hepatic forms of FMO from mouse are similar enzymes that are immunologically related and show only a few minor differences.

Amino Acid Sequence↗
PubMed1994

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 enrichment 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 C18 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 l at concentrations levels of 0.1-5 micrograms/l were used for application of the method. Both adsorbents provided recoveries of 75-95%. The limits of detection were 0.08-0.60 micrograms/l with NPD and 0.03-0.13 micrograms/l with MS-SIM.

Gas Chromatography-Mass Spectrometry↗
PubMed1993

Carcinogenicity of azathioprine: an S-AR investigation.

Besides its use in the treatment of a variety of presumed autoimmune diseases, azathioprine is given as an immunosuppressant to patients who have had renal transplants. Though epidemiological studies have provided "sufficient" evidence of its carcinogenicity in humans, the carcinogenicity tests in rats and mice are considered to be inconclusive because of limitations in the design and results of these tests (IARC, 1981, 1987). Rosenkranz and Klopman (1991) used the CASE program to identify the structural features responsible for its carcinogenicity. They concluded that this genotoxic chemical was a carcinogen due to the presence of the molecular fragment C"-S-C=. The finding was based on the presence of this biophore fragment in five other compounds, namely: 2-amino-5-nitrothiazole, 2-mercaptobenzothiazole, fenthione, 4,4'-thiodianiline and nithiazide. Recently, Ashby (1992) has expressed concern over the validity of their findings. With the aim of contributing to this debate on the mechanism of carcinogenicity of azathioprine, we have analyzed the structural basis of carcinogenicity of azathioprine and the five support compounds using the carcinogenicity predictor of our toxicity prediction program, TOPKAT. The results, more in line with Ashby's concerns, indicate that no molecular fragment involving the S atom is associated with the carcinogenic properties of these molecules. According to the TOPKAT program the carcinogenicity, if any, of azathioprine is due to the NO2 electrophile because its other major structural features are found to be either associated with non-carcinogenicity or do not discriminate carcinogens from non-carcinogens.

Algorithms↗
PubMed1989

A freshwater shrimp (Paratya compressa improvisa) as a sensitive test organism to pesticides.

The susceptibility of 2-week-old individuals of the freshwater shrimp, Paratya compressa improvisa, to five kinds of insecticide and five kinds of herbicide was examined in comparison with that of two species of Cladocera, Daphnia magna and Moina macrocopa. The shrimp was especially sensitive to two organophosphorus insecticides. The 48-h LC50 values for fenitrothion and fenthion to the shrimp were 1.15 and 1.04 microg litre(-1) (mean value, n=2), in contrast with 37.8 and 35.3 microg litre(-1) in the case of M. macrocopa, and more than 50 microg litre(-1) with D. magna. The shrimp also showed the higher susceptibility to other insecticides, diazinon, carbaryl (NAC) and BPMC, apart from D. magna to diazinon and NAC. The shrimp also showed higher susceptibility to herbicides. The 48-h LC50 values of CNP, benthiocarb, oxadiazon, butachlor, and symetryne to the shrimp were two to eight times lower than those of two species of Cladocera, except for the LC50 value of oxadiazon to M. macrocopa, which was very slightly higher. However, the shrimp showed a somewhat lower susceptibility to heavy metals than the two species of Cladocera, especially to copper, and to cadmium and zinc in comparison with D. magna. A bioassay using the shrimp with river water, collected from the river adjacent to the paddy field, showed clearly the high mortality of the shrimp following the aerial spraying with pesticides.

Journal Article↗
PubMed1991

Differences in the mode of lethality produced through intravenous and oral administration of organophosphorus insecticides in rats.

This study was undertaken to investigate the possibility that mechanisms other than cholinesterase (ChE) inhibition account for the acute toxicity of organophosphorus insecticide. Both the P = O type insecticide (direct ChE inhibitors: chlorfenvinphos and dichlorvos) and the P = S type insecticide (indirect ChE inhibitors: diazinon and fenthion) were employed. Rats treated with lethal doses of intravenous and oral P = O type insecticides and oral P = S type insecticides exhibited typical signs of anti-ChE poisoning along with marked inhibition of brain and erythrocyte ChE activity. In contrast, rats given lethal doses of intravenous P = S type insecticides exhibited tonic convulsions and opisthotonos, with only slight inhibition of ChE activities. When P = O type insecticides were intravenously administered to anesthetized and conscious rats, animals exhibited typical anti-ChE poisoning signs in cardiorespiration: hypertension and apnea which were antagonized by atropine. After administration of lethal doses of P = O type insecticides, breathing disappeared before the cessation of heart beats. Rats receiving lethal doses of intravenous P = S type insecticides did not show hypertension, but exhibited transient cessation of breathing and heart beats. Breathing was observed after the disappearance of heart beats. The electroencephalogram (EEG) was characterized by spike and wave complexes. The EEG and cardiorespiratory changes were not antagonized by atropine. It was concluded that lethality following intravenous P = S type insecticides may be independent of ChE inhibition.

Administration, Oral↗
PubMed1995

Tick resistance to pyrethroids in New Caledonia.

Boophilus microplus is the common cattle tick of great economic importance in New Caledonia. Since 1986, deltamethrin has been used for dipping. In 1992, an increase of tick infestations was seen on some ranches. Field and laboratory studies were conducted to determine if resistant ticks were present. Ticks resistant to deltamethrin were detected on three ranches, with resistance factors from 8.3 to 97.7. All deltamethrin-resistant isolates were also resistant to fenvalerate, but only one was also resistant to flumethrin. The combination of deltamethrin and ethion seemed to be active on isolates. This is the second description of isolates of Boophilus microplus resistant to pyrethroids, the first being in Australia and points to future problems in the management of tick control. Some organophosphates like chlorpyriphos or fenthion were studied as replacements for deltamethrin, in spite of the fact that most ticks are resistant to ethion. The authors propose a rotation strategy based on the alternation of several compounds together with a minimal frequency of dipping.

Animals↗
PubMed1988

Acute organophosphorus insecticide poisoning in Sri Lanka.

Records of 92 cases of acute organophosphorus (OP) insecticide poisoning were analysed. Of the patients 91% were under 30 years of age and 86% were males. The common agents were Dimethoate, Methamidophos, Malathion, Monocrotophos and Fenthion. Poisoning was due to ingestion with suicidal intent in the majority. In addition to the acute cholinergic features, the other important manifestations were delayed onset respiratory paralysis and delayed polyneuropathy. The overall mortality was 18%.

Adolescent↗
PubMed2005

A preliminary assessment of consumer's exposure to pesticide residues in fisheries products.

The fisheries products in this study comprise fish, bivalve, crustacean and cephalopod collected from different types of markets in Taiwan between the years 2001 and 2003. A total of 91 pesticide residues belonging to four major pesticide groups were tested and analyzed. The test results show that 65.40% of fish, 93.55% of shellfish, 84.92% of crustacean and 98.33% of cephalopod samples contain no detectable residues. There are only two kinds (organochlorine and organophosphate) of totally six pesticides (DDTs, dieldrin, chlorpyrifos, fenitrotion, fenthion and prothion) that have been detected from the fisheries products in this study. For there were pesticides present in the fish products, consumption of fisheries product there was no zero risk. But the exposure of consumer did not exceed the acceptable daily intakes (ADI). For male, there was the highest risk in exposure to dieldrin, which the percentage of ADI was 93.56%. This study also suggests that a yearly monitoring program for organophosphate pesticide residues in fish is necessity.

Animals↗
PubMed2004

Determination of organophosphorus pesticides using membrane-assisted solvent extraction combined with large volume injection-gas chromatography-mass spectrometric detection.

Eight organophosphorus pesticides (parathion-methyl, fenitrothion, malathion, fenthion, bromophos, bromophos-ethyl, fenamiphos and ethion) in aqueous samples were analysed by means of membrane-assisted solvent extraction. First a 20 ml extraction vial was filled with 15 ml of aqueous sample. Then the membrane bag consisting of nonporous polypropylene was put into the vial and filled with 800 microl of organic solvent. The analytes were separated from the aqueous layer by transporting them through the membrane material into the small amount of solvent. The technique was fully automated and successfully combinable with large volume extraction and GC-MS. To achieve an optimum performance several extraction conditions were investigated. Cyclohexane was chosen as acceptor phase. Then the impact of salt, methanol, pH value, as well as working parameters like stirring rate of the agitator and extraction time, were studied. Moreover, the influence of matrix effects was examined by adding different concentrations of humic acid sodium salt. Detection limits in the ng/l level were achieved using large volume injection with the injecting volume of 100 microl. The recovery values ranged from 47 to 100% and the relative standard deviation for three standard measurements was between 4 and 12% (except for bromophos-ethyl: 22%). The linear dynamic range was between 0.001 and 70 microg/l. The applicability of the method to real samples was tested by spiking the eight organophosphorus pesticides to red wine, white wine and apple juice samples.

Beverages↗
PubMed2004

Evaluation of common organic solvents for gas chromatographic analysis and stability of multiclass pesticide residues.

In this study, we evaluated the suitability of six common organic solvents for gas chromatographic (GC) analysis of pesticides. Three of these, acetone, acetonitrile (MeCN) and ethyl acetate (EtAc), represent extraction solvents commonly used in multiresidue methods for determination of pesticides in produce. The other three, isooctane, hexane and toluene, often serve as exchange solvents before a GC analysis. An ideal solvent for GC analysis of multiclass pesticide residues should be compatible with: the analytes, sample preparation, and GC analysis. This study addresses each aspect with emphasis placed on stability of selected pesticides in the given solvents. In this respect, the exchange solvents proved to be superior to the more polar extraction solvents. Degradation of N-trihalomethylthio fungicides (e.g., captan, folpet, dichlofluanid) in MeCN was observed only in certain lots of the tested MeCN, but even if it occurred, the stability of these analytes as well as that of dicofol and chlorothalonil was dramatically improved by the addition of 0.1% (v/v) acetic acid. Dicofol and chlorothalonil were also unstable in acetone, and pesticides with a thioether group (e.g., fenthion, disulfoton) degraded in the tested EtAc. Formation of isomers of certain pyrethroids (deltamethrin, lambda-cyhalothrin) was recorded in the chromatograms from MeCN and acetone solutions, but this effect more likely occurred during the GC injection than in solution. For several reasons, MeCN was found to be the most suitable solvent for extraction of a wide polarity range of pesticide residues from produce. After acidification, the stability of problematic pesticides in MeCN is acceptable, and MeCN can also serve as a medium for GC injection; therefore solvent exchange is generally not required before GC analysis. If sensitivity is an issue in splitless injection, then toluene was demonstrated to be the best exchange solvent due to its miscibility with MeCN and stronger responses of relatively more polar pesticides (e.g., acephate, methamidophos) as compared to hexane and isooctane.

Organic Chemicals↗
PubMed2005

Pesticide exposure of non-occupationally exposed subjects compared to some occupational exposure: a French pilot study.

Data about non-dietary exposure to different chemical classes of pesticides are scarce, especially in France. Our objective was to assess residential pesticide exposure of non-occupationally exposed adults, and to compare it with occupational exposure of subjects working indoors. Twenty unexposed persons, five gardeners, seven florists and nine veterinary workers living in Paris area were recruited. Nineteen residences, two greenhouses, three florist shops and three veterinary departments were then sampled. Thirty-eight insecticides, herbicides and fungicides were measured in indoor air with an air sampler for 24 h, and on hands by wiping them with isopropanol-wetted swabs. After extraction, samples were analysed by gas and high-performance liquid chromatography. Seventeen different pesticides were detected at least once in indoor air and twenty-one on the hands. An average of 4.2+/-1.7 different pesticides was detected per indoor air sample. The organochlorines lindane, alpha-endosulfan and alpha-HCH were the most frequently detected compounds, in 97%, 69% and 38% of the samples, respectively. The organophosphates dichlorvos and fenthion, the carbamate propoxur and the herbicides atrazine and alachlor were detected in more than 20% of the air samples. Indoor air concentrations were often low, but could reach 200-300 ng/m(3) in residences for atrazine and propoxur. Propoxur levels significantly differed between the air of veterinary places and other places (Kruskal-Wallis test, p<0.05) and dieldrin levels between residences and workplaces (p<0.05). There was a greater number of pesticides on hands than in air, with an average of 6.3+/-3.3 different pesticides detected per sample, the most frequently detected being malathion, lindane and trifluralin, in more than 60% of the subjects. Maximal levels (up to 1000-3000 ng/hands) were observed either in the general population or in workers, depending on the pesticide. However, no significant difference was observed between workers and general population handwipe pesticide levels. As expected, gardeners were exposed to pesticides sprayed in greenhouses. Florists and veterinary workers, whose pesticide exposure had not been described until now, were also indirectly exposed to pesticides used for former pest control operations. Overall, general population was exposed to more various pesticides and at levels sometimes higher than in occupational places. The most frequent pesticides in residences were not the same as in US studies but levels were similar. These preliminary results need to be confirmed in a greater number of residences from different parts of the country, in order to better assess pesticide exposure of the general population and its influencing factors.

Acetamides↗
PubMed2005

Predicting skin permeability from complex chemical mixtures.

Occupational and environmental exposure to topical chemicals is usually in the form of complex chemical mixtures, yet risk assessment is based on experimentally derived data from individual chemical exposures from a single, usually aqueous vehicle, or from computed physiochemical properties. We present an approach using hybrid quantitative structure permeation relationships (QSPeR) models where absorption through porcine skin flow-through diffusion cells is well predicted using a QSPeR model describing the individual penetrants, coupled with a mixture factor (MF) that accounts for physicochemical properties of the vehicle/mixture components. The baseline equation is log k(p) = c + mMF + a sigma alpha2(H) + b sigma beta2(H) + s pi2(H) + rR2 + vV(x) where sigma alpha2(H) is the hydrogen-bond donor acidity, sigma beta2(H) is the hydrogen-bond acceptor basicity, pi2(H) is the dipolarity/polarizability, R2 represents the excess molar refractivity, and V(x) is the McGowan volume of the penetrants of interest; c, m, a, b, s, r, and v are strength coefficients coupling these descriptors to skin permeability (k(p)) of 12 penetrants (atrazine, chlorpyrifos, ethylparathion, fenthion, methylparathion, nonylphenol, rho-nitrophenol, pentachlorophenol, phenol, propazine, simazine, and triazine) in 24 mixtures. Mixtures consisted of full factorial combinations of vehicles (water, ethanol, propylene glycol) and additives (sodium lauryl sulfate, methyl nicotinate). An additional set of 4 penetrants (DEET, SDS, permethrin, ricinoleic acid) in different mixtures were included to assess applicability of this approach. This resulted in a dataset of 16 compounds administered in 344 treatment combinations. Across all exposures with no MF, R2 for absorption was 0.62. With the MF, correlations increased up to 0.78. Parameters correlated to the MF include refractive index, polarizability and log (1/Henry's Law Constant) of the mixture components. These factors should not be considered final as the focus of these studies was solely to determine if knowledge of the physical properties of a mixture would improve predicting skin permeability. Inclusion of multiple mixture factors should further improve predictability. The importance of these findings is that there is an approach whereby the effects of a mixture on dermal absorption of a penetrant of interest can be quantitated in a standard QSPeR model if physicochemical properties of the mixture are also incorporated.

Algorithms↗
PubMed2005

Comparative studies on the effects of water, ethanol and water/ethanol mixtures on chemical partitioning into porcine stratum corneum and silastic membrane.

The effects of water and ethanol vehicles on stratum corneum and silastic membrane partitioning of 11 industrial and agricultural compounds were studied to aid in characterizing and assessing risk from skin exposure. Zero percent, 50% and 100% aqueous ethanol solutions were used as solvents for (14)C labeled phenol, 4-nitrophenol, pentachlorophenol, dimethyl parathion, parathion, chloropyrifos, fenthion, triazine, atrazine, simazine and propazine. Compound partitioning between the solvents and porcine stratum corneum/silastic membrane were estimated. Stratum corneum was exposed to aqueous ethanol ranging from 0% to 100% v/v ethanol in 20% increments and Fourier transform infrared spectroscopy (FT-IR) was used to obtain an index of lipid disorder. Gravimetry and FT-IR were used to demonstrate lipid extraction in aqueous ethanol solutions. Partitioning patterns in silastic membranes resembled those in stratum corneum and were correlated with octanol/water partitioning. Partitioning was highest in water and was higher from 50% ethanol than from 100% ethanol, except for parathion, 4-nitrophenol, atrazine and propazine. Correlation existed between molecular weight and partitioning in water, but not in ethanol and ethanol/water mixtures. Lipid order, as reflected in FT-IR spectra, was not altered. These studies suggest that stratum corneum partitioning of the compounds tested is primarily determined by relative compound solubility between the stratum corneum lipids and the donor solvent. Linear relationships existed between octanol/water partitioning and stratum corneum partitioning. Partitioning was also correlated with molecular weight in water solvent systems, but not in ethanol and ethanol/water mixtures. Ethanol and ethanol/water mixtures altered the stratum corneum through lipid extraction, rather than through disruption of lipid order.

Animals↗
PubMed2005

Effect of vehicles and sodium lauryl sulphate on xenobiotic permeability and stratum corneum partitioning in porcine skin.

Dermal contact with potentially toxic agricultural and industrial chemicals is a common hazard encountered in occupational, accidental spill and environmental contamination scenarios. Different solvents and chemical mixtures may influence dermal absorption. The effects of sodium lauryl sulphate (SLS) on the stratum corneum partitioning and permeability in porcine skin of 10 agricultural and industrial chemicals in water, ethanol and propylene glycol were investigated. The chemicals were phenol, p-nitrophenol, pentachlorophenol, methyl parathion, ethyl parathion, chlorpyrifos, fenthion, simazine, atrazine and propazine. SLS decreased partitioning into stratum corneum from water for lipophilic compounds, decreased partitioning from propylene glycol and did not alter partitioning from ethanol. SLS effects on permeability were less consistent, but generally decreased permeability from water, increased permeability from ethanol and had an inconsistent effect on permeability from propylene glycol. It was concluded that, for the compounds tested, partitioning into the stratum corneum was determined by the relative solubility of the solute in the donor solvent and the stratum corneum lipids. Permeability, however, reflected the result of successive, complex processes and was not predictable from stratum corneum partitioning alone. Addition of SLS to solvents altered partitioning and absorption characteristics across a range of compounds, which indicates that partition coefficients or skin permeability from neat chemical exposure should be used with caution in risk assessment procedures for chemical mixtures.

Agrochemicals↗
PubMed2006

Foetal and adult human CYP3A isoforms in the bioactivation of organophosphorothionate insecticides.

In humans organophosphorothionate pesticides (OPT) prenatal exposure has been demonstrated. Since OPT-induced neurodevelopmental effects may be due to in situ bioactivation by foetal enzymes, the catalytic activity of the foetal CYP3A7 toward chlorpyrifos (CPF), parathion (PAR), malathion (MAL) and fenthion (FEN) has been assessed by using recombinant enzymes. A comparison with the adult isoforms CYP3A4 and CYP3A5 has been also carried out. CYP3A7 was able to produce significant levels of oxon or sulfoxide from the four OPTs in the range of tested concentrations (0.05-200 microM). When the efficiencies of CYP3A isoforms were compared, the ranking, expressed as CLi values, were: CPF=3A4>3A5>3A7; PAR=3A4>>3A7>>3A5; MAL=3A4>3A7>3A5; FEN (sulfoxide formation)=3A4>3A5>>3A7. The CYP3A5 efficiency appeared to be more dependent on the single insecticide than its related isozyme CYP3A4. Our results indicate that the levels of toxic metabolite formed in situ by CYP3A7 from CPF, MAL and PAR but not from FEN have the chance to inhibit acetylcholinesterase, following prenatal exposure to OPTs. However, due to the smaller weight of foetal liver, the contribution to total OPT biotransformation is relatively low. On the other hand, our results clearly indicate that at low CPF concentrations, the formation of the non-toxic metabolites is highly favoured in the foetus.

Animals↗
PubMed2000

Mixed-level orthogonal array design for the optimization of solid-phase extraction of some pesticides from surface water.

An orthogonal array design (OAD), OA32(4(1) x 2(28)), was employed as a chemometric method for the optimization of the solid-phase extraction (SPE) of atrazine, diazinon, ametryn and fenthion in surface water. Seven parameters: the type of eluting solvent, type of sorbent, flow-rate of eluting solvent, sample pH, sample volume, elution volume, addition of modifier and flow-rate of water sample were studied and optimized by a mixed-level OAD. The effects of these factors and some two-variable interactions on the recovery of the pesticides were quantitatively evaluated by the analysis of variance and percentage contribution techniques. The final optimized condition was employed for the SPE of selected micro-organic pollutants from Karoun river water, south of Iran. Atrazine and ametryn were tentatively identified and determined at the 0.7 and 0.9 microg l(-1) level, respectively.

Chromatography, Liquid↗
PubMed2001

Optimization of headspace solid-phase microextraction conditions for the determination of organophosphorus insecticides in natural waters.

Headspace solid-phase microextraction (HS-SPME) has been developed for the analysis of seven organophosphorus insecticides, i.e. diazinon, fenitrothion, fenthion, ethyl parathion, methyl bromophos, ethyl bromophos and ethion in natural waters. Their determination was carried out using gas chromatography with flame thermionic and mass spectrometric detection. To perform the HS-SPME, two types of fibre have been assayed and compared: polyacrylate (PA 85 microm), and polydimethylsiloxane (PDMS 100 microm). The main parameters affecting the HS-SPME process such as temperature, salt additives, memory effect, stirring rate and adsorption-time profile were studied. The method was developed using spiked natural waters such as ground, sea, river and lake water in a concentration range of 0.05-1 microg/l. The HS-SPME conditions were optimized in order to obtain the maximum sensitivity. Detection limits varied from 0.01 to 0.04 microg/l and relative standard deviations (RSD <17%) were obtained showing that the precision of the method is reliable. The method showed also good linearity for the tested concentration range with regression coefficients ranging between 0.985 and 0.999. Recoveries were in relatively high levels for all the analytes and ranged from 80 to 120%. Water samples collected from different stations along the flow of Kalamas river (NW Greece) were analyzed using the optimized conditions in order to evaluate the potential of the proposed method to the trace-level screening determination of organophosphorus insecticides. The analysis with HS-SPME has less background interference and the advantage of its non-destructive nature reveal the possibility of the repetitive use of the SPME fibre.

Gas Chromatography-Mass Spectrometry↗
PubMed2002

Application of solid-phase microextraction in the monitoring of priority pesticides in the Kalamas River (N.W. Greece).

A solid-phase microextraction (SPME) method was applied to an extended monitoring survey of priority pesticides for the European Union for a period of 12 months in water of the Kalamas River (Epirus region of northwestern Greece) in order to determine their concentrations and seasonal variations. Polydimethylsiloxane-coated fiber (100 microm) was used. The samples were screened using gas chromatography with flame thermionic detection. Detection was confirmed by gas chromatographymass spectroscopy. The most frequently detected pesticides were some of the more commonly used herbicides, such as S-ethyl-N,N-di-n-propylthiol carbamate (EPTC), trifluralin, atrazine, deethylatrazine, terbuthylazine and alachlor, and insecticides, such as carbofuran, diazinon, disulfoton, parathion methyl, parathion ethyl, fenthion and ethion. Concentrations of individual compounds ranged from 0.020 to 0.3 microg/L. Greater pesticide concentrations occurred during the seasons of application. A comparison with a well-established solid-phase extraction (C18 disks) procedure was performed for samples of high-season application (May-September) in order to confirm the effectiveness of the SPME technique. The results demonstrate the suitability of the SPME method for routine screening multiresidue analysis in natural waters.

Chromatography, Gas↗