Aldicarb Sulphoxide Research Articles

Poisoning of cats and dogs by the carbamate pesticides aldicarb and carbofuran

The intentional and accidental poisoning of animals and people is a threat to public health and safety worldwide. Necropsies and histopathological examinations of 26 cats and 10 dogs poisoned by the carbamates aldicarb and carbofuran, confirmed by thin layer chromatography (TLC) and high performance liquid chromatography with diode-array detector (HPLC-DAD) were analysed, with variable post mortem interval and conservation of the carcass. Biological matrices were collected for toxicological and histopathological analyses. High performance liquid chromatography with diode-array detector (HPLC-DAD) was utilized to detect aldicarb and its metabolites, aldicarb sulphoxide and aldicarb sulphone, and carbofuran. The variable post mortem interval and the method of conservation of the carcass may be harmful to toxicological, necroscopic and histopathological analyses, that should be performed in order to provide reliable evidences to investigate possible poisoning of animals, which is cruel crime, and are usually linked to domestic or social conflict.

Poisoning by illegal rodenticides containing acetylcholinesterase inhibitors (chumbinho): a prospective case series

Objective. To describe a prospective case series of poisonings caused by ingestion of illegal rodenticides containing acetylcholinesterase inhibitors, mainly “chumbinho,” followed-up by the Campinas PCC for a period of 1 year. Case series. Seventy-six cases were included, of which 53.9% were males. Age ranged from 2 to 74 years (median = 36 years). The main circumstances leading to poisoning were intentional (suicide attempts 92.1%; homicide attempts 5.3%), and 65.8% were admitted less than 2 hours after ingestion. Most of the patients (96.1%) showed cholinergic muscarinic manifestations, particularly salivation (86.8%), myosis (77.6%), sweating (50%), and bronchorrhea (35.5%). Atropine was used in 82.9% of patients (median = 2 days), intubation and mechanical ventilation in 46.1% (median = 3 days), and the median length of the hospital stay was 4 days. Plasma samples obtained upon admission in 59 cases revealed (LC-MS/MS): aldicarb (55), carbofuran (2), aldicarb and carbofuran (1), no active component (1). In most of the plasma and urine samples collected upon admission, the highest concentrations (ng/mL) obtained were for the active metabolite aldicarb sulphoxide (plasma, median = 831, IIQ = 99.2–2885; urine, median = 9800, IIQ = 2000–15000) than aldicarb (plasma, median = 237, IIQ = 35.7–851; urine, median = 584, IIQ = 166–1230), indicating rapid metabolism. The excretion of aldicarb and its metabolites was rapid since these compounds were rarely detected in plasma samples 48 hours after admission. Sequential cholinesterase analysis in 14 patients revealed almost complete reactivation in the first 48 hours post-admission, compatible for poisoning by carbamates. Based on the Poisoning Severity Score, the cases were classified as asymptomatic (5.3%), minor (11.8%), moderate (35.5%), severe (43.4%), and fatal (3.9%). Conclusions. Most poisonings involved aldicarb and resulted from suicide attempts; the poisonings were generally severe, with a mortality of 3.9%. Aldicarb was rapidly absorbed, metabolized, and excreted.

Solid-phase extraction for multi-residue analysis of pesticides in honey

A fast and simple multi-residue method for the analysis of 15 organophosphorus (OP), 17 organochlorine (OC), 8 pyrethroids (PYR), 12 N-methyl-carbamate (NMC) pesticide residues and bromopropylate in honey is presented. Ready–to–use EXtrelut®NT 20 column, eluted with dichloromethane, was used to extract the pesticide residues from the aqueous-acetone honey sample, obtaining a clean extract directly analyzable. Determination was carried out by gas chromatography (GC) coupled with flame photometric detector (FPD) for OP compounds and by GC coupled with mass spectrometry detector (MSD) for OC and PYR pesticides and bromopropylate. The NMC pesticides were analysed by liquid chromatography-double derivatization coupled with spectrofluorimetric detector (LC/DD/Fl). This method allows the determination of the 53 pesticide residues at low concentrations (0.0005–0.074 mg/kg) and can be used to assess the compliance with the Maximum Residues Levels (MRLs) set by the European Union. The performance of the method was evaluated and specificity, linearity, recovery, repeatability, reproducibility, limit of quantification (LOQ) and limit of detection (LOD) were determined. A good linearity (r2⩾ 0.99) was found in the range 0.0005–0.074 mg/kg for the majority of the compounds studied. Most of the pesticides had recoveries in the range 70–103 % and values of relative standard deviation (RSD) < 20 for repeatability and reproducibility, showing good accuracy and precision of the method. Aldicarb partially degraded in aldicarb sulphoxide during the analytical procedure, giving anomalous values. The LOQ for all pesticides investigated was from 0.0005 to 0.025 mg/kg while the LOD ranged from 0.0002 to 0.008 mg/kg.

In‐capillary microextraction using monolithic polymers: Application to preconcentration of carbamate pesticides prior to their separation by MEKC

In the present work we report a novel procedure for in-capillary microextraction using a monolithic polymeric sorbent. In the proposed methodology, sample treatment takes place in the CE instrument but in a different capillary from that used for the electrophoretic separation. Polymers based on butyl methacrylate and divinylbenzene formed in situ inside a capillary column were assayed. The best results were found with the divinylbenzene-based polymers. The usefulness of the proposed procedure was checked for the determination of carbamate pesticides (Methomyl, Asulam, Carbendazim, Aldicarb, Carbetamide, Propoxur, Pirimicarb, Carbaryl, Carbofuran and Methiocarb) and three of their degradation compounds (Aldicarb sulphoxide, 2-isopropoxyphenol and alpha-naphthol) using MEKC. The optimization of the MEKC is reported, a good separation of the 13 analytes being obtained in less than 6 min. The analytical method using in-capillary microextraction was validated in terms of linearity, repeatability, precision (RSD< or =18% for 50 microg/L), and LODs (1-16 microg/L), and it revealed the usefulness of this in-capillary preconcentration procedure for the determination of analytes of intermediate polarity.

Monitoring of N-methylcarbamate pesticides in the Pinios River (central Greece) by HPLC

Seasonal variations of N-methylcarbamate pesticides in Pinios River waters of central Greece were determined for a period of one year (January to December 2003). The water samples were collected every month from four sampling sites. Liquid–liquid extraction followed by HPLC was used for the determination of 10 carbamate pesticides. The ranges of the most commonly encountered pesticides in the surface river water were for carbofuran 25–206 ng L−1, aldicarb nd–69 ng L−1, aldicarb sulphoxide 5–107 ng L−1, methomyl nd–86 ng L−1, 3-hydroxycarbofuran nd–117 ng L−1, propoxour nd–91 ng L−1, carbaryl 10–100 ng L−1, and methiocarb 7–117 ng L−1. The higher concentrations in river water were measured during the period of May to October, following seasonal application, and diminished significantly during the autumn and winter. The highest concentrations of the carbamate pesticides were detected in sampling site 2 (Piniada), near an area with intense agricultural activity. This work clearly demonstrates that agricultural practices in the agricultural area of Thessaly have degraded the quality of surface waters. N-methylcarbamate pesticides data obtained in this study were statistically analysed by two-way analysis of variance (ANOVA). It was proved that both seasonal and spatial variations are significant sources for the total variance, the latter making a greater contribution than the former.

Residues of aldicarb in oranges: a unit-to-unit variability study

Residues of aldicarb and its sulphoxide and sulphone oxidative metabolites in individual Navelino orange trees were determined at several time intervals after soil application of TEMIK 10G at 200g formulated material per tree. Analysis was by HPLC with postcolumn derivatization giving average recoveries of 98% for aldicarb (RSD 6%), 34% for aldicarb sulphoxide (RSD 5%) and 77% for aldicarb sulphone (RSD 5%). Lowest calibrated levels (LCLs) were 0.02mg/ kg for aldicarb and aldicarb sulphone and 0.04mg/kg for aldicarb sulphoxide. At the recommended preharvest interval (PHI) of 120 days no detectable residues of any compound, including the parent compound, were found in any of the samples analysed. In mature fruits (PHI of 88 days) detectable residues at the LCL for aldicarb sulphoxide and 0.03 or 0.04 mg/kg for aldicarb sulphone were found in only three of the 18 samples analysed. In immature fruits detectable residues of aldicarb sulphoxide at concentrations ranging between 0.04 (LCL) and 0.51mg/kg were detected in 70 out of 88 samples analysed, while residues of aldicarb sulphone at concentrations 0.02 (LCL) to 0.8mg/kg were detected in 73 out of 88 samples. Indicative variability factors for sulphoxide and sulphone were estimated for immature fruits.

Analysis of N-methylcarbamates insecticides and some of their main metabolites in urine with liquid chromatography using diode array detection and electrospray mass spectrometry

Commonly used N-methylcarbamates, i.e., aldicarb and carbofuran and some of their main metabolites as aldicarb sulphoxide and aldicarb sulphone for aldicarb and 3-hydroxycarbofuran for carbofuran were extracted from human urine by off-line solid phase extraction with graphite carbon and subsequently clean up with NH 2-modified silica. Analyte fractionation and quantification were performed by liquid chromatography (LC) with UV detection. The recovery efficiencies of the tested compounds yielded more than 81% at the fortification level of 0.05 μg/ml in urine and their relative standard deviations were between 6 and 16%. The detection limits of each compound ranged between 4 and 10 μg/l. This method involves confirmatory analysis by LC–electrospray mass spectrometry (MS) instrumentation equipped with a single quadrupole mass filter. MS data acquisition was performed by time-scheduled selected ion monitoring (SIM) program. Limits of detection giving values between 0.1 and 0.5 μg/l. Urine samples from a pest control operator were analyzed and the analytes were not found.

Reversed-phase liquid chromatographic column switching for the determination of N-methylcarbamates and some of their main metabolites in urine

A column switching system for the determination of some polar pesticides and their main metabolites, such as aldicarb, aldicarb sulphoxide, aldicarb sulphone, carbofuran and 3-hydroxicarbofuran, in human urine has been developed. The limits of detection were between 0.3 and 1 μg/l. We used a simple solid-phase extraction with graphite carbon and a RPLC–LC analysis with UV detection yielding average recoveries between 84 and 110% ( N=5) with RSD between 4 and 8%.

Determination of the rate of aldicarb sulphoxidation in rat liver, kidney and lung microsomes

1. The rate of sulphoxidation of aldicarb (2-methyl- 2-(methylthio) propanal O-[(methylamino)carbonyl oxime], Temik®) in rat hepatic, renal and pulmonarymicrosomes was determined by quantitating the levels of aldicarb sulphoxide and aldicarb sulphone produced during incubations. Under in vitro experimental conditions used in the present study, aldicarb sulphoxide was the only metabolite produced, and further metabolism of aldicarb sulphoxide to aldicarb sulphone was negligible. 2. The average maximal velocity (μmol/min/mg protein) for the sulphoxidation of aldicarb, based on measurements of product formation, in liver, kidney and lung microsomes was 5·41, 39·51 and 2·45 respectively. The corresponding values for the Michaelis constant (μM) were 184, 1050 and 188 respectively. 3. These results imply that under in vivo conditions (1) aldicarb sulphoxidation is not likely to be saturable even at lethal doses in the rat, and (2) aldicarb clearance in rat liver and kidney will be limited by the rate of blood flow and not metabolizing enzyme levels.

The use of cultured hepatocytes from goats and cattle to investigate xenobiotic oxidative metabolism.

The oxidative metabolism of aldicarb (ALD), a carbamate pesticide, and fenbendazole (FBZ), an anthelmintic, was studied using cultured hepatocytes obtained from 4 goats and a bullock and incubated with ALD (50 mumol/L) and FBZ (10 mumol/L). The parent compounds and the metabolites were measured by HPLC. Both compounds are metabolized at the sulphur atom via two sequential oxidations, first to the sulphoxide (aldicarb sulphoxide and oxfendazole, respectively) and then to the sulphone. Oxfendazole and fenbendazole sulphone from FBZ, and aldicarb sulphoxide from ALD were found in both species. Aldicarb sulphone was not produced by the hepatocyte preparations from the bullock. The good correlation obtained comparing the in vitro results of FBZ metabolism with published in vivo data obtained on FBZ kinetics in the same species confirmed the usefulness of in vitro models for predictive analysis of in vivo xenobiotic biotransformations.

Photodegradation of the carbamate pesticides aldicarb, carbaryl and carbofuran in water

The photodegradation of the pesticides aldicarb, carbofuran and carbaryl. in distilled, pond and artificial sea-water samples with or without humic acids was examined. In addition, two different light sources, a xenon arc lamp and a high-pressure mercury lamp, were used to compare the photolysis behaviour. The effect of temperature on hydrolysis was also studied. The major photodegradation products were identified by matching their diode-array spectra with the corresponding spectra of the authentic standards, using peak purity software of the diode array and their retention times. Aldicarb sulphoxide was the major photodegradation product from aldicarb whereas 1-naphthol was the main hydrolysis product from carbaryl. Acetone (5%) was added as a photosensitizer in this instance. For carbofuran, one main unidentified hydrolysis product was detected. Analyses were made by direct injection of water samples into a liquid chromatograph with diode-array detection.

Applications of thermospray liquid chromatography-mass spectrometry in photochemical studies of pesticides in water

Thermospray liquid chromatography-mass spectrometry (TSP-LC-MS) in the positive- and negative-ion modes (PI and NI, respectively) was used for the characterization of the pesticides aldicarb, carbaryl, cyanazine, fenitrothion, linuron and parathion-methyl, including the corresponding photodegradation products. The LC analyses were performed on RP-18 columns using methanol-water (70:30 or 50:50) + 0.05 M ammonium acetate or 0.05 M ammonium formate. Photodegradation studies of pesticides in distilled water were performed using a suntest apparatus, except for fenitrothion, for which a high-pressure mercury lamp was used because of slow photodegradation. The main photodegradation pathways corresponded to dealkylation, deamination, dehalogenation and hydroxylation. Photodegradation experiments were carried out using solutions of the different pesticides at 10–200 ppm in distilled water. For carbaryl photolysis is very slow in distilled water, so 5% of acetone was needed as photosensitizer. When PI-mode TSP-LC-MS was employed, aldicarb sulphoxide, monolinuron, hydroxysimazine and fenitrooxon could be identified as breakdown products of aldicarb, linuron, cyanazine and fenitrothion, respectively. In NI-mode TSP-LC-MS aldicarb sulphoxide, 1-naphthol and p-nitrophenol could be identified as the main degradation products of aldicarb, carbaryl and parathion-methyl, respectively. As all the pesticides were dissolved in methanol for solubility reasons, methoxy analogues of the degradation products of cyanazine were also identified. In the PI mode of operation the base peak generally corresponded to [M + H] + for cyanazine and its photodegradation products and to [M + NH 4] + for linuron, aldicarb and fenitrothion and their corresponding degradation products. For carbaryl [M + NH 4] + was also the base peak, but its main photodegradation product, 1-naphthol, could only be identified under NI conditions. In the NI mode of operation different processes such as proton abstraction, (dissociative) electron capture and anion attachment, take place. Fragment ions such as [M] ·− for aldicarb sulphoxide, the main photodegradation product of aldicarb, [M - H] − for 1-naphthol and [M - CONHCH 3] − for carbaryl and anion attachment ions corresponding to [M + CH 3COO] − for aldicarb sulphoxide and 1-naphthol and to [M - CONHCH 3 + CH 3COOH] − for carbaryl were formed. A tentative photodegradation pathway for the different pesticides in water is postulated.

Rapid on-line precolumn high-performance liquid chromatographic method for the determination of benomyl, carbendazim and aldicarb species in drinking water

A reversed-phase high-performance liquid chromatogrpahic (HPLC) method has been developed for the determination of trace concentrations of benomyl, carbendazim, aldicarb, aldicarb sulphoxide and aldicarb sulphone in drinking water. A 10-ml sample of water is passed through a 3-cm precolumn, packed with 5-μm C 8 sorbent, at a flow-rate of 5 ml/min. The HPLC system is then switched to an acetonitrile-water gradient elution program. The preconcentrated analytes are eluted from, and separated by, the 3-cm C 8precolumn and determined by UV absorption. The total analytical time is 25 min. The lowest detectable concentrations are in the range of 2.5 · 10 −9 – 11.0 · 10 −9 g/ml for the five analytes investigated with 10 ml of sample.

Role of flavin-containing monooxygenase in the in vitro biotransformation of aldicarb in rainbow trout (Oncorhynchus mykiss)

1. The in vitro biotransformation of 14C-aldicarb was examined in liver, kidney, and gill microsomes from the rainbow trout (Oncorhynchus mykiss). 2. In all tissues the major metabolite was aldicarb sulphoxide. Addition of the cytochrome P-450 inhibitor, N-benzylimidazole, failed to alter significantly aldicarb sulphoxide levels, while co-incubation with the flavin-containing monooxygenase substrates, N,N-dimethylaniline or methimazole, caused significant decreases in sulphoxide formation in liver and gill microsomes. 3. Aldicarb sulphoxide formation was optimal at pH 8.0, and had Michaelis-Menten kinetics with an apparent Km of 46.7 microM and a Vmax of 0.216 nmol/min per mg. 4. Aldicarb sulphoxide formation was competitively inhibited by co-incubation with N,N-dimethylaniline in liver microsomes. These data indicate that flavin-containing monooxygenase plays an important role in the in vitro biotransformation of aldicarb in rainbow trout.

Gas chromatographic determination of aldicarb and its metabolites in urine

A method is described for the determination of aldicarb and its metabolites (the sulphoxide and sulphone) in urine by gas chromatography with flame photometric detection (GC-FPD). The sample was concentrated with a column containing activated charcoal and Florisil, and then eluted with dichloromethane-acetone (1:1, v/v). The aldicarb and aldicarb sulphoxide in the eluate solution were oxidized to aldicarb sulphone and the total sulphone concentration was determined by GC-FPD after extraction with dichloromethane and clean-up with an activated charcoal column. The detection limit was 0.0024 mg/l. The mean recoveries from spiked urine in the range 0.04-0.12 mg/l were 90.9%,86.6%,92.6% for aldicarb, aldicarb sulphoxide and aldicarb sulphone, respectively.

Accelerated degradation of aldicarb and its oxidation products in previously treated soils

The persistence of aldicarb, aldicarb sulphoxide and aldicarb sulphone was studied in soils used for crops grown commercially and in experimental soils with different histories of treatment with a granular formulation of aldicarb. Total aldicarb residues declined more rapidly in incubations in all the previously treated soils (initial 50% loss in 5–17 days at 15°C) than in the corresponding untreated soils (initial 50% loss in 25–50 days). This was largely because of more rapid breakdown of aldicarb sulphoxide and, to a lesser extent, of aldicarb sulphone. Accelerated degradation was induced more readily by pretreatment with carbofuran than with aldicarb or thiofanox and seemed to be influenced at least as much by dose level as by frequency of pretreatment. It is concluded that rotation of chemical usage should suppress development of the phenomenon with commercially recommended doses of aldicarb but that the potential for cross-enhancement is still little understood.

Reactive pre-concentration of trace amounts of pesticides in environmental analysis procedures. Part I. Determination of carbamates by indirect spectrophotometry.

A method is described for the indirect spectrophotometric determination of aldicarb (Temik)[2-methyl-2-(methylthio)propionaldehyde O-methylcarbamoyl oxime] at trace levels in aqueous samples. The procedure starts with nucleophilic cleavage of aldicarb on a small column packed with a strongly basic anion exchanger, also providing quantitative sorption of the resulting oximate. Subsequent addition of sulphuric acid results in the in situ formation and elution of hydroxylamine, later used to reduce quantitatively an equivalent amount of FeIII to FeII. FeII is determined spectrophotometrically via the formation of the red FeII-bathophenanthroline complex. Elution recoveries were virtually 100% with standard deviations of less than 1% for the detection of 2.5 × 10–6M aldicarb, pre-concentrating 200 ml of a 1 µg ml–1 analyte solution. Larger sample volumes permit pre-concentration factors of up to 100. Thus, 500-ml water samples were spiked to contain 25 ng ml–1(initial concentration) of either aldicarb, aldicarb sulphoxide, aldicarb sulphone or methomyl. After 25-fold pre-concentration, analyte recoveries were 95% or better using the indirect spectrophotometric determination.

The role of ferrous ions in the rapid degradation of oxamyl, methomyl and aldicarb in anaerobic soils

AbstractThe carbamoyloxime pesticides methomyl, oxamyl and aldicarb, together with the oxidation products of aldicarb, are known to break down much more rapidly in certain anaerobic subsoils than in the aerobic topsoils from the same site. Ferrous ions have now been shown to be involved in this reaction. Oxamyl was degraded in aqueous solutions at 30°C containing 250 μg ml−1 Fe2+ with a half‐life of about 10 h, independent of pH in the range of 5.65–7.66; the observed products of this reaction were N,N‐dimethyl‐l‐cyanoformamide and methanethiol. These same products, rather than the oximino hydrolysis product observed from degradation in aerobic soils, were rapidly and quantitatively formed from oxamyl in suspensions of anaerobic reduced subsoils (Fe2+ concentration 27–41 μg ml−1 soil water), but oxamyl was rather stable in water‐saturated Vredepeel subsoil (Fe2+ concentration 0.65 μg ml−1) in which the redox potential was much higher. Methomyl behaved similarly. The rates of reaction in the suspensions of anaerobic subsoils were greater than expected from the concentrations of Fe2+ in the soil water, but most of the Fe2+ present in soil was bound to the soil particles by cation exchange and this bound Fe2+ may have participated. Breakdown of aldicarb was accelerated both in solutions of Fe2+ and in the suspensions of anaerobic reduced subsoils, though the rate enhancement was less than observed with methomyl and oxamyl; 2‐methyl‐2‐methylthiopropionitrile and 2‐methyl‐2‐methylthiopropionaldehyde were the observed products from aldicarb in anaerobic soil but only the former was produced in Fe2+ solutions; the corresponding nitriles and aldehydes were also yielded by aldicarb sulphoxide and aldicarb sulphone in the anaerobic, reduced subsoils.

Temik contamination in a surface water system and its potential effect on a daphnid species in Florida

Preliminary sampling of the Caloosahatchee River, which serves as a source of drinking water for the city of Ft Myers, Florida, showed that aldicarb, aldicarb sulphoxide and aldicarb sulphone had contaminated the river. These toxicants are associated with the pesticide Temik. Concentrations of total residue were as high as 17·9 μg litre −1 at one site, but contaminants were never detected in final (treated) drinking water. Concentrations of only 10 μg litre −1 of aldicarb sulphoxide have significant impacts on the life history characteristics of a common Florida daphnid, Daphnia laevis. We suggest that Temik use in Florida, and perhaps elsewhere, may prove detrimental to the biota of surface water systems.

The distribution of aldicarb and its metabolites between Lumbricus terrestris, water and soil

AbstractAldicarb is taken up by earthworms from aqueous solution to give concentrations in the worms comparable to that in the external aqueous solutions. Uptake from waterlogged soils is similar, but much less aldicarb is taken up from drier soils. Aldicarb sulphoxide [2‐methyl‐2‐(methylsulphinylpropionaldehyde O‐methylcar‐bamoyloxime], aldoxycarb and oxamyl are poorly taken up, giving concentrations in the worm of about 5% of the external aqueous concentration. In worms, aldicarb is rapidly converted to the sulphoxide which has a half‐life in worms of 19 h at 15°C, and 50 h at 5°C.