Death by chumbinho: aldicarb intoxication-regarding a corpse in decomposition.

Chumbinho is the popular name given to carbamate aldicarb (Temik), an insecticide commonly used in agriculture and highly toxic (LD50 = 0.9 mg/kg oral in rats) that has been sold clandestinely in several regions of Brazil. Chumbinho is sold illegally as raticide and is available in a formulation of small black granules which are easily mixed with food for criminal purposes, its use often being attributed to accidents and suicides, hence the importance of its inclusion in the toxicology studies of suspicious deaths. With the corpse putrefaction, many pathological and toxicological anatomical parameters are damaged or lost. This study emphasizes the importance of the gastric content observation, which in this case has, despite the advanced putrefaction, recognized the presence of chumbinho and guide its toxicological confirmation.

Effect of ammonium on liquid- and gas-phase protonation and deprotonation in electrospray ionization mass spectrometry.

The electrospray ionization (ESI) is a complex process and there has been a long debate regarding the gas-phase effect on ion generation in the process. In this paper we investigated the effect of liquid chromatographic mobile phase additives (formic acid, aqueous ammonia and their combination) on the ESI signal intensities for a wide variety of compounds. The addition of a trace amount of aqueous ammonia to the common formic acid-methanol mobile phase significantly enhances the ESI signals of protonated molecules and suppresses the formation of sodium adduct ions. This effect is well observed for the compounds containing the -N-C=O group but not for those without N or O atoms. The ESI signal intensity of deprotonated molecules increases with increase in pH of the mobile phase for neutral compounds, such as substituted urea, whereas this trend is not observed for acidic compounds such as phenoxy acids. The mechanistic analysis regarding liquid- and gas-phase protonation and deprotonation is discussed.

Determination of parathion, aldicarb, and thiobencarb in tap water and bottled mineral water in Mashhad, Iran.

Water is a necessity for life. Currently, because of different contaminations in tap water, most people prefer using bottled mineral waters. Pesticides (e.g., organophophorous, carbamates, etc.) are among the most dangerous chemicals that may be found in drinking waters, which can cause long- and short-term complications. Because all people consume at least 2 L of water per day, water-quality monitoring is vital. In this study, we determined the concentration of three pesticides (aldicarb, parathion, and thiobencarb) in 13 tap-water samples collected from 13 different urban areas and 10 samples of bottled mineral water in Mashhad, a major city in northeast Iran. Samples were analyzed by gas chromatography coupled with a pulsed flame photometric detector after solid-phase extraction. Results showed that 2 of 13 tap-water samples and 2 of 10 bottled mineral water trademarks were contaminated either by parathion or by thiobencarb or both, with concentrations ranging between 0.6 and 0.8 ppb. According to the defined guideline values, determined concentrations of pesticides are below the permissible World Health Organization level for these toxic agents, and it is considered that drinking these tap waters and bottled mineral waters are safe for human consumption.

Pesticide residues and dietary risk assessment in radishes in Shandong.

Pesticide residues in radishes can induce serious health hazards, especially in children and toddlers. In order to assess potential health risk from pesticide residues in radishes, a total of 26 pesticides were evaluated by gas chromatography with mass spectrometry in 1690 samples, which were collected from the year 2016 to 2019 in Shandong Province of China. All the 26 pesticide residues were detected in 752 radish samples (44.50%), but only 221 samples (13.08%) contained detectable pesticide residues, which are above the maximum residue limits (MRLs). Multiple residues with two to nine pesticides were present in 5.09% (86 out of 1690) of samples. Hazard quotient (HQ) and the cumulative risk index were far below 100, while percentage value of acute reference dose (%ARfD) of triazophos exceeded 100 for adults, children, and toddlers. The %ARfD value for carbofuran, aldicarb, monocrotophos, and parathion was over 100 for toddlers. From the perspective of public health, the occurrence of pesticide residues in radishes could not pose a serious health risk problem, but the acute health risk should be paid more attention, especially to toddlers. It is recommended to make strict regulations on the management of pesticide residues and human health risk assessment about pesticide residues.

Fluorescence tuning behavior of carbon quantum dots with gold nanoparticles via novel intercalation effect of aldicarb.

A simple, sensitive and rapid fluorometric system has been developed for the detection of aldicarb (ALD) based on inner filter effect (IFE) of gold nanoparticles (AuNPs) on fluorescence (FL) intensity of carbon quantum dots (CQDs). Addition of CQDs into AuNPs, gets them aggregated due to electrostatic interaction resulting in quenching the FL intensity of CQDs. With addition of ALD into AuNPs, an intercalated layer was formed between them through Au-N and Au-S bond which reduced IFE of AuNPs. Hence, CQDs FL intensity recovered along with ALD concentration varying between 3.8 and 76 µg L-1 with lower detection limit of 3.02 µg L-1. The spiked real samples study in fruits, vegetables and soft drinks revealed that this sensing platform was repeatable and effective for real samples. The validation of proposed method indicates that the ALD sensor is promising and adaptable for everyday on spot environment and food safety monitoring.

Summary of potable well monitoring conducted for aldicarb and its metabolites in the United States in 2005.

United States potable well monitoring in the Pacific Northwest, California, Texas, Mississippi delta, and the Southeast was conducted in 2005 to provide estimates of dietary exposure to aldicarb carbamate residues (aldicarb and its two carbamate metabolites) in potentially vulnerable potable wells. Samples were analyzed from 1,673 drinking water wells in nine major use areas that were within 300 m of fields treated at least once with aldicarb between 2002 and 2005. Analyses were performed with a high-performance liquid chromatography/tandem mass spectrometry analytical method with limits of quantitation of 0.021 microg/L for aldicarb and aldicarb sulfone and 0.027 microg/L for aldicarb sulfoxide. The method detection limits were 0.0070 microg/L for aldicarb and aldicarb sulfone and 0.0090 microg/L for aldicarb sulfoxide. Samples from 1,513 of the 1,673 wells contained no aldicarb carbamate residues. Only 10 wells had total aldicarb carbamate residues above 1 microg/L, the maximum being 2.9 microg/L. All residues were below the U.S. Environmental Protection Agency Health Advisory Limit (HAL) of 10 microg/L. Given the number of samples collected in this study, there is a 95% confidence level that the maximum concentration in this study exceeds the 99.8th percentile of concentrations of all potable wells located within 300 m of fields recently treated with aldicarb. Therefore, the data from this study show that the restrictions and management practices on the current product label continue to be effective in preventing residues in excess of the 10 microg/L HAL in potable wells in these use areas.

Aging of biomixtures: Effects on carbofuran removal and microbial community structure.

The aim of this work was to determine the efficiency of a straw/compost/soil biomixture for pesticide depuration during its aging and continuous use, for a period of over a year, based on its capacity to remove carbofuran (CFN), while simultaneously monitoring the variations in microbial community structure. Successive CFN spikings were applied in the biomixture at 6-week intervals, and the removal efficiency was determined 48 h post-application. Initially, only a discrete degradation performance was observed (9.9%), but one CFN application was sufficient to induce efficient elimination (>88.5%) of the pesticide at subsequent influxes for a period of over 6 months. A statistically significant reduction on CFN removal efficiency after this time was detected, reaching levels similar to the fresh-prepared biomixture (14.8%) at the end of the experiment. Simultaneous DGGE analyses showed only modest changes on microbial community patterns through time for both, bacteria and fungi. The clustering of genetic fingerprints in chronological groups corresponding to significantly different CFN degradation efficiencies indicates that biomixture aging changes not only the composition of microbial communities, but also their suitability to engage in pesticide degradation. Periodic substitution of straw/compost/soil biomixture in biopurification systems or regular provision of easily-degradable organic substrates should be considered to maintain an adequate depuration capacity on this system.

Effect of surfactants on desorption of aldicarb from spiked soil.

Surfactant enhanced desorption of aldicarb from spiked soil was investigated in this paper. Anionic (sodium dodecyl benzene sulphonate, SDBS), cationic (hexadecyl trimethyl ammonium bromide, HTAB) and nonionic (octyl polyethylene glycol phenyl ether, OP) surfactants were tested to determine their optimal desorption conditions including desorption time, mixing speed and surfactant concentrations. The results showed that the optimal operating conditions were obtained at 2 h, 150 rpm, and surfactants concentrations were 1000, 100, and 200 mg l(-1) for SDBS, OP, and HTAB, respectively. The paper also investigated the desorption efficiency of mixture of different kinds of surfactants for aldicarb-spiked soil, and found that anionic-nonionic surfactant mixtures gave the best desorption efficiency up to 77%, while anionic-cationic surfactant mixture gave a poor desorption efficiency similar to water, suggesting that mixture of anionic-nonionic surfactants were highly promising on remediation of aldicarb-contaminated soil.

Determination of pesticides in soy-based infant formula using liquid chromatography with electrospray ionization tandem mass spectrometry.

A sensitive method using liquid chromatography with electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) was developed and validated to quantify and confirm 13 pesticides, including aldicarb sulfoxide, aldicarb sulfone, oxamyl, methomyl, formetanate, 3-hydroxycarbofuran, carbendazim, thiabendazole, aldicarb, propoxur, carbofuran, carbaryl, and methiocarb, in soy-based infant formula. Data acquisition under MS/MS was achieved by applying multiple reaction monitoring of 2 fragment ion transitions to provide a high degree of sensitivity and selectivity for both quantitation and confirmation. Different approaches to constructing calibration curves were compared and discussed to address issues of the extraction efficiency or recovery, and matrix effects. Matrix-matched standard calibration curves with the use of isoprocarb as an internal standard were finally used to achieve the best accuracy of the method. Under most circumstances, recoveries of 13 pesticides, spiked at 5.0, 25.0, and 45.0 microg/kg, were close to 100%. The method detection limits (signal-to-noise ratio > or =3:1; microg/kg) of 13 pesticides were 0.2 for thiabendazole and methiocarb, 0.6 for aldicarb, and 0.1 for the others.

Exhumation of Wistar rats experimentally exposed to the carbamate pesticides aldicarb and carbofuran: A pathological and toxicological study.

Exhumation is required for the investigation of suspicions deaths when a body is buried and is usually performed under court order. Exhumation of animals is not a routine practice in forensic pathology. In this study, 30 male 70-day-old Wistar rats were experimentally exposed to the carbamate pesticides aldicarb and carbofuran. Toxicological, macroscopic and microscopic examinations were performed. Groups of 3 animals (2 exposed and 1 control) were evaluated at 24h, 3days, 5days, 7days and 10days post-mortem. In histopathological examination, the brain, liver, lungs and kidneys were assessed, and for toxicological analysis, the gastric contents, liver, vitreous humor, skeletal muscle and larvae (when available) were collected. The pesticides were detected by HPLC and quantified in the analyzed matrices, and a possible delay in tissue putrefaction due to the pesticides was observed. This study has revealed that it is possible to exhume animals for investigations of possible poisoning by carbamates and has demonstrated that the exhumation of an animal in a suspected case of poisoning should not be ruled out. The increasing demand for investigations of suspicious animal deaths, e.g., in cases of poisoning, will likely lead to an increase in the use of this type of procedure in veterinary pathology.

Fluorescence biosensing strategy based on mercury ion-mediated DNA conformational switch and nicking enzyme-assisted cycling amplification for highly sensitive detection of carbamate pesticide.

Pesticides are of great importance in agricultural and biological fields, but pesticide residues may harm the environment and human health. A highly sensitive fluorescent biosensor for the detection of carbamate pesticide has been developed based on acetylcholinesterase (AChE)-catalyzed hydrolysis product triggered Hg(2+) release coupled with subsequent nicking enzyme-induced cleavage of a duplex DNA for cycling amplification. In this protocol, two DNA probes, an unmodified single-stranded helper DNA probe 1 (HP1) and a quencher-fluorophore probe (QFP) are ingeniously designed. HP1 can be folded into hairpin configuration through T-Hg(2+)-T base pair formation. QFP, labeled with FAM and BHQ1 at its two terminals, contains the recognition sequence and the cleavage site of the nicking enzyme. In the presence of carbamate pesticide, the activity of AChE is inhibited, and the amount of the product containing the thiol group generated by the hydrolysis reaction of acetylthiocholine chloride (ACh) decreases, resulting in the release of a low concentration of Hg(2+). The number of HP1 that can be selectively unfolded would be reduced and the subsequent nicking enzyme-assisted cleavage processes would be affected, resulting in decreased fluorescence signals. The fluorescence intensity further decreases with the increase of the pesticide concentration. Therefore, the pesticide content can be easily obtained by monitoring the fluorescence signal change, which is inversely proportional to the logarithm of the pesticide concentration. The detection limit of aldicarb, the model analyte, is 3.3 µgL(-1), which is much lower than the Chinese National Standards or those previously reported. The as-proposed method has also been applied to detect carbamate pesticide residues in fresh ginger and artificial lake water samples with satisfactory results, which demonstrates that the method has great potential for practical application in biological or food safety field.

Pesticide contamination of the coastline of Martinique.

In January and February 2002, the presence of certain agricultural pesticides throughout the coastline of the Caribbean island of Martinique was investigated. The tropical climate of the French West Indies is suitable for banana production, which requires intensive use of pesticides. An inventory of all pesticides used on the island (compounds and tonnage) was compiled. Surveys and analyses revealed the presence of pesticides in the plumes of seven rivers. The organochlorine chlordecone and metabolites of aldicarb were detected at nearly all of the monitored sites, even though the use of chlordecone has been prohibited since 1993. Two triazines (ametryn and simazine) were also identified. The concentrations of carbamates and triazines detected in the water and sediment samples from Martinique are comparable to those reported for mainland France. Chlordecone concentrations in the sediment and particulate matter samples were, however, particularly high in the samples from Martinique. Toxicological implications are discussed. Of particular concern are the high levels of chlordecone (which is bioaccumulating and carcinogenic) and further monitoring of this compound is recommended, especially in fish and other sea-food products.

Acetylcholinesterase biosensor for inhibitor measurements based on glassy carbon electrode modified with carbon black and pillar[5]arene.

New acetylcholinesterase (AChE) biosensor based on unsubstituted pillar[5]arene (P[5]A) as electron mediator was developed and successfully used for highly sensitive detection of organophosphate and carbamate pesticides. The AChE from electric eel was immobilized by carbodiimide binding on carbon black (CB) placed on glassy carbon electrode. The working potential of 200mV was obtained in chronoamperometric mode with the measurement time of 180 s providing best inter-biosensors precision of the results. The AChE biosensor developed made it possible to detect 1×10(-11)-1×10(-6) M of malaoxon, 1×10(-8)-7×10(-6) M of methyl-paraoxon, 1×10(-10)-2×10(-6) M of carbofuran and 7×10(-9)-1×10(-5) M of aldicarb with 10 min incubation. The limits of detection were 4×10(-12), 5×10(-9), 2×10(-11) and 6×10(-10) M, respectively. The AChE biosensor was tested in the analysis of pesticide residuals in spiked samples of peanut and beetroot. The protecting effect of P[5]A derivative bearing quaternary ammonia groups on malaoxon inhibition was shown.

Construction of an acetylcholinesterase-choline oxidase biosensor for aldicarb determination.

In this study, acetylcholinesterase and choline oxidase were co-immobilized on poly(2-hydroxyethyl methacrylate) membranes and the change in oxygen consumption upon aldicarb introduction was measured. Immobilization of the enzymes was achieved either by entrapment or by surface attachment via a hybrid immobilization method including epichlorohydrin and Cibacron Blue F36A activation. Immobilized enzymes had a long-storage stability (only 15% activity decrease in 2 months in wet storage and no activity loss in dry storage). Aldicarb detection studies showed that a linear working range of 10-500 and 10-250 ppb aldicarb could be achieved by entrapped and surface immobilized enzymes, respectively. Enzymes immobilized on membrane surfaces responded to aldicarb presence more quickly than entrapped enzymes. Aldicarb concentrations as low as 23 and 12 ppb could be detected by entrapped and surface immobilized enzymes, respectively, in 25 min.

Determination of binary pesticide mixtures by an acetylcholinesterase-choline oxidase biosensor.

In this study, acetylcholinesterase (AChE) and choline oxidase (ChO) were co-immobilized on poly(2-hydroxyethyl methacrylate) (pHEMA) membranes to construct a biosensor for the detection of anti-cholinesterase compounds. pHEMA membranes were prepared with the addition of SnCl(4) to achieve the desired porosity. Immobilization of the enzymes was done by surface attachment via epichlorohydrin (Epi) and Cibacron Blue F3G-A (CB) activation. Enzyme immobilized membrane was used in the detection of anti-cholinesterase activity of aldicarb (AS), carbofuran (CF) and carbaryl (CL), as well as two mixtures, (AS+CF) and (AS+CL). The total anti-cholinesterase activity of binary pesticide mixtures was found to be lower than the sum of the individual inhibition values.

Detection of pesticides using an amperometric biosensor based on ferophthalocyanine chemically modified carbon paste electrode and immobilized bienzymatic system.

A new highly sensitive amperometric method for the detection of organophosphorus compounds has been developed. The method is based on a ferophthalocyanine chemically modified carbon paste electrode coupled with acetylcholinesterase and choline oxidase co-immobilized onto the surface of a dialysis membrane. The activity of cholinesterase is non-competitively inhibited in the presence of pesticides. The highest sensitivity to inhibitors was found for a membrane containing low enzyme loading and this was subsequently used for the construction of an amperometric biosensor for pesticides. Analyses were done using acetylcholine as substrate; choline produced by hydrolysis in the enzymatic layer was oxidized by choline-oxidase and subsequently H(2)O(2) produced was electrochemically detected at +0.35 V vs. Ag/AgCl. The decrease of substrate steady-state current caused by the addition of pesticide was used for evaluation. With this approach, up to 10(-10) M of paraoxon and carbofuran can be detected.

Evaluation of the decarbamylation process of cholinesterase during assay of enzyme activity.

The activity of carbamylated cholinesterase increases continuously during assay, suggesting that progressive decarbamylation takes place. The following effects of assay conditions on the observed decarbamylation were studied: the effect of the sulfhydryl group of nitrobenzoate produced in the course of Ellman assay, the effect of substrate and the effect of sample dilution during assay. This study indicates that sample dilution is the main trigger to the decarbamylation observed during assay of cholinesterase activity. The process was described as a first-order reaction during which the inhibited enzyme gives place to the active form. Kinetic constants for decarbamylation of human pseudocholinesterase (EC 3.1.1.8) at 30 degrees C were approximately 0.005 min-1 for dimethylcarbamates and 0.010 min-1 for monomethylcarbamates, when 1 mmol/l propionylthiocholine was used as substrate.

Determination of aldicarb, aldicarb sulfoxide and aldicarb sulfone in tobacco using high-performance liquid chromatography with dual post-column reaction and fluorescence detection.

A screening method for the determination of aldicarb (AS) and its sulfoxide (ASX) and sulfone (ASN) metabolites in tobacco at low ppm levels is described. Tobacco samples are extracted using methanol with the aid of sonication at ambient conditions. The extract is filtered and then injected into a high-performance liquid chromatograph equipped with a dual post-column reaction system and a fluorescence detector. Chromatographic separation is performed on a C18 column with a mixture of methanol-acetonitrile-water containing 0.1% of triethanolamine as the mobile phase. Triethanolamine is added to improve peak shape of AS residues and to reduce the undesired interaction between residual silanols and interferences, mainly amino acids and other amines. The average recoveries for AS residues spiked in tobacco are higher than 95% for AS, 91% for ASN and 85% for ASX at levels of 0.5-10 ppm (w/w). The detection limit is 0.5 ppm for each of the target compounds.

Considerations on ultra trace analysis of carbamates in water samples.

A new routine method for the ultra trace analysis of carbamates in water samples is presented, using solid-phase extraction followed by high-performance liquid chromatography coupled to atmospheric pressure electrospray ionisation mass spectrometry (SPE-LC-ESI-MS). Instrumental conditions of LC-ESI-MS in the selected ion monitoring (SIM) mode, showed excellent linear response for the six N-methyl carbamates studied (aldicarb, carbaryl, carbofuran, methomyl, oxamyl and pirimicarb) in the range from 1 to 50 microg/l and a precision having a relative standard deviation below 7.8% was achieved. Instrumental limits of detection of 0.10 microg/l were found for these carbamates, with the exception of methomyl for which 0.50 microg/l was measured. The SPE assays were shown to be easy, fast, very sensitive, requiring a low volume (50 ml) of water sample. For laboratory-spiked water samples having 0.03 and 0.30 microg/l of individual N-methyl carbamates, higher selectivities were achieved in cartridges having octadecylsilica, polystyrene-divinylbenzene and N-vinylpyrrolidane-divinylbenzene as solid phases, for which reasonable average recoveries were obtained. Ten replicates using octadecylsilica SPE cartridges, showed average recoveries between 73.7 and 92.6% with a relative standard deviation lower than 14.7%. The present methodology evidences good robustness, accuracy and precision for monitoring of N-methyl carbamates in water samples, and is shown to be a suitable alternative to replace the currently dedicated analytical systems. The limits of detection for the analysis of N-methyl carbamates in water samples reached in the present methodology (0.5 to 3 ng/l), clearly cover the maximum concentration admissible for pesticides, established by the European Union directive on water quality.

Determination of aldicarb, aldicarb sulfoxide and aldicarb sulfone in some fruits and vegetables using high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

An analytical method for the determination of aldicarb, and its two major metabolites, aldicarb sulfoxide and aldicarb sulfone in fruits and vegetables is described. Briefly the method consisted of the use of a methanolic extraction, liquid-liquid extraction followed by solid-phase extraction clean-up. Afterwards, the final extract is analyzed by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-APCI-MS). The specific fragment ion corresponding to [M-74]+ and the protonated molecular [M+H]+ ion were used for the unequivocal determination of aldicarb and its two major metabolites. The analytical performance of the proposed method and the results achieved were compared with those obtained using the common analytical method involving LC with post-column fluorescence detection (FL). The limits of detection varied between 0.2 and 1.3 ng but under LC-FL were slightly lower than when using LC-APCI-MS. However both methods permitted one to achieve the desired sensitivity for analyzing aldicarb and its metabolites in vegetables. The method developed in this work was applied to the trace determination of aldicarb and its metabolites in crop and orange extracts.