Aminocarb water

High performance Hquid chromatography with electrochemical detection has been used to determine 2—7 ppb of carbamate pesticides in water (40). The investigated pesticides were aminocarb, asulam, j -butylphenyknethylcarbamate (BPMC), carbaryl, carbenda2im, chlorpropham, desmedipham, and phenmedipham. 

CASRN 2032-59-9 molecular formula C11H16N2O2 FW 208.26 Plant/Surface Water. Several transformation products reported by Day (1991) include 4-amino-/n-tolyl-7V-methylcarbamate (AA), 4-amino-3-methylphenol (AC), 4-formamido-/n-tolyl-TV-methylcarbamate (FA), 7V-(4-hydroxy-2-methylphenyl)-yV-methylformamide (FC), 4-methyl-formamido-/n-tolyl-7V-methylcarbamate (MFA), 4-methylamino-/n-tolyl-Wmethylcarbamate (MAA), 3-methyl-4-(methylamino)phenyl-Wmethylcarbamate (MAC), phenol, methylamine, and carbon dioxide. MAA was not detected in natural water but was detected in fish tissues following exposure to aminocarb-treated water in the laboratory. The metabolites FA, AC, and MAC were detected in Canadian forests treated with aminocarb but the metabolites AA, MAA, and FC were not detected (Day, 1991). 

Chemical/Physical. Aminocarb was hydrolyzed in purified water to 4-(dimethylamin-o)-3-methylphenol before yielding o-methylbenzoquinone. This compound then oxidized to 6-(di-methylamino)-2-methyl-1,4-benzoquinone, 6-(methylamino)-2-methyl-l,4-benzoquinone, 5-(di-methylamino)-2-methyl-1,4-benzoquinone, and 5-(methylamino)-2-methyl-l,4-benzoquinone... 

Leger, D.A. and Mallet, V.N. New degradation products and a pathway for the degradation of aminocarb [4-(dimethylamino)-3-methylphenyl IV-methylcarbamate] in purified water, J. Agric. Food Chem., 36(1) 185-189, 1988. 

The insecticide aminocarb has also been used extensively in eastern Canada on budworm control operations. Fenitrothion has been applied as a water emulsion (New Brunswick) and an oil solution (Quebec), but aminocarb because of its formulation characteristics, has been only applied operationally as an oil solution. Analysis of spruce foliage (7) showed aminocarb had a half life of 5 to 6 days with complete disappearance by 64 days post spray. Subsequent work (8) confirmed the short half life of aminocarb on coniferous foliage (3.2 to 6.9 days), and showed that the half life was dependant on the initial concentration of the insecticide. The material was found to be highly labile and dissipated rapidly and the authors made the statement that with these characteristics... 

In the last year a new formulation of aminocarb has appeared on the insecticide market. It is finely ground aminocarb suspended in an oil and it has the advantage that it can be tank mixed to give either an oil or a water suspension. Studies (10) show that, like the oil solution, this product has a half life in the same range (3.2 to 6.0 days). There was an indication of a variation in the initial rate of loss due to the physical characteristics of the water emulsion spray (in a series of repeat studies the evaporation rate was not constant). The presence of the emulsifier inhibited evaporation resulting in a higher initial foliar deposit than with the oil base spray. The occurence of the lower rate of deposit of the oil spray can be attributed to the particular oil used in the Canadian budworm sprays. To meet the concerns of the health authorities the standard No. 2 and No. 4 fuel oils which had been used are now prohibited. The accepted product, known as Insecticide Diluent 585 is volatile with an evaporation rate approaching that of water. 

In studies on the residue levels of aminocarb in a litter-soil mixture (samples taken to a depth of 10 cm) there was no detectable material even at the first post spray sample which was 14 hours after application (7). In this particular study the aminocarb had been applied at 70 g Al/ha in 0.42 1/ha. Aminocarb was found in foliage and water. 

Laboratory Studies on Insecticide Degradation. Degradation in natural waters Stream water (pH 6.0) and sediment (organic content 36%) were taken from a small shallow stream (depth ca 20 cm, width oa 1.5 m) in the Goulais River watershed, a mixed conifer-deciduous forest area, ca 50 km northeast of Sault Ste. Marie, Ont., Canada. Two degradation studies in duplicate (one for aminocarb and another for fenitrothion) were set up according to Sundaram and Szeto ( 1 ). Aminocarb and fenitrothion (100 pg/L in acetone) were added separately to 1000 mL aliquots of sterilized (Ameco Sterilizer 1 h) and unsterilized stream water in either open or closed 1500 mL Erlenmeyer flasks. The latter were sealed with polyethylene snap caps which were removed once a day for about 1 min. to allow air exchange. The flasks were incubated at 15 0.2°C in an environmental chamber. Unfortified water... 

Dissipation in stream water with sediment In a concurrent study, a series of 120, 100 g aliquots of coarsely sifted stream sediment were placed in 500 mL Erlenmeyer flasks containing 200 mL of stream water each. One half of the samples, i.e., 60 flasks, were autoclaved as before in an Ameco sterilizer for 1 h. After they were cooled to room temperature, all samples including the 60 non-autoclaved samples were separated into two sets (20 autoclaved + 20 non-autoc laved for each set) and one set was fortified with aminocarb and the other with fenitrothion in acetone to a level of 100 ppb (30 yg/ 300 g) and incubated in an environmental chamber as described above. The remaining 40 flasks served as controls for both experiments. Samples of both the autoclaved and the non-autoclaved water and sediment in open and closed flasks as well as control samples were analyzed for the active ingredients 1.0 h after fortification (zero time) and thereafter at intervals of time up to 75 h.. 

Except demethylated fenitrothion, all other metabolites found in water in the earlier study, were also identified in sediments for both the insecticides. Amino-fenitrothion, nitrocresol and monodemethylated aminocarb (MA) were most frequent compared to other metabolites. 

Two fenitrothion and one aminocarb tank mixes were studied, all containing Triton X-100 (p-tert-octylphenoxynonaethoxy-ethanol), a nonionic surfactant, and water. One fenitrothion tank mix also contained cyclosol, a petroleum distillate. The percent (vol.) composition of different ingredients present in the tank mixes, the streams sprayed with them and their discharge, and dates and rates of application are summarized in Table I. 

Model Ecosystem Studies. Dissipation of aminocarb and fenitrothion in stream water Measurements of the concentrations (ppb) of fortified aminocarb and fenitrothion in the stream water as a function of time (t [h]), and graphing of the data (Figure 1 and 2) showed that the concentration of these two insecticides decreased exponentially with time and followed the first-order rate... 

Figure 1. Degradation of aminocarb in fortified natural and sterile stream water in open and closed flasks.

The decrease in concentration of fenitrothion from spiked stream water samples was faster compared to aminocarb. The concentration of the former decreased to 10 ppb in non-autoclaved open flasks in 75 h, while aminocarb concentrations fell to 21 ppb in the same period. A similar increased loss for fenitrothion was also found in closed flasks (32 ppb VS 39 ppb) as well as in autoclaved (open, 24 ppb VS 44 ppb and closed 57 ppb vs 67 ppb) flasks, indicating that at pH 6.0, fenitrothion is more readily lost than aminocarb. Increased stability of aminocarb in acidic waters is probably due to its nucleophilicity leading to protonation and forming an aryldimethylammonium cation... 

Movement and degradation of aminocarb in water/sediment mode 1 The concentrations of aminocarb in water and sediment at different intervals during incubation are presented graphically in Figure 3. During the experimental period, the concentration of aminocarb in water in non-autoclaved flasks decreased from 92 (open) and 95 (closed) ppb to 11 and 21 ppb respectively, while... 

Figure 3. Movement and degradation of aminocarb in a water/sediment model.

Residual concentrations of aminocarb in water as well as in sediment were higher in autoclaved samples because of the absence of microbial activity. The pattern of mobility of the chemical from water to sediment was similar to that observed in non-auto-claved samples, but its overall persistence was higher and because of this, a gradual buildup of the active ingredient in sediment occurred in the closed flask. Most of the aminocarb was likely adsorbed onto particulate matter in suspension and then gradually settled in the sediment. Nearly 97% of the fortified aminocarb remained in the autoclaved sample (closed flask) at the end of experiment out of this 34% was in water and 63% was adsorbed onto sediment. In contrast, 51% of the fortified amount of aminocarb remained in the open flask, of which 26% was in water and the rest in sediment. Sediments, like water, contained detectable levels of demethylated aminocarb moieties as well as the phenol, but among them, the monodemethylated derivative (methylamino Matacil) was predominant compared to the other two metabolites. 

Movement and degradation of fenitrothion in the water/sed-iment model The concentration of fenitrothion in non-autoclaved and autoclaved stream waters in the presence of sediment are shown in Figure 4. The concentration of fenitrothion decreased rapidly in water and increased rapidly in sediment, showing that fenitrothion has a greater tendency than aminocarb for translocation from water to sediment. Within 15 h, 94% (open flask) and 89% (closed flask) of the chemical in the non-autoclaved samples was lost from the aqueous phase and the corresponding concentrations in sediment were 43% and 66% respectively. The rapid translocation of this compound from water to sediment was probably due to its lipophilic nature (], ). Such a phenomenon was not very significant for aminocarb because it was present in water as a cationic species at pH 6.0. At the end of the experimental period (75 h), only 0.2% and 0.5% of the chemical remained in water whereas the sediments contained 19% and 31% of the fortified levels respectively. The rapid loss in the open flask is primarily attributable to volatilization coupled with some microbial degradation. In the absence of volatilization (closed flasks), the decrease in concentration in both the phases was lower. The presence of sediment therefore,... 

The magnitude of kj depends upon the nature of the chemical under investigation. In the present study, it is evident that fenitrothion has a higher degree of adsorption (kj k2) compared to aminocarb although it is claimed that aminocarb is strongly adsorbed to soil particles (9). In acidic waters (pH 6.0), aminocarb exists as a protonated cation... 

In conclusion, water/sediment model studies suggest that the dissipation pathways for aminocarb and fenitrothion would be primarily via volatilization and microbial action as schematically represented in Figure 5. 

Figure 5. Dissipation pathways of aminocarb and fenitrothion in water/sediment model systems.

Table III shows the levels of aminocarb present in mayfly nymphs sampled from Portage Brook following the 1st application. Aminocarb concentrations found in insects were not high and no breakdown products of the insecticides were found. The peak concentration detected is only 20 ppb (1 h post-application) exposed to a maximum of 2.26 ppb aminocarb in water, representing a concentration factor of oa 9. Residues declined to below detection limits ( < 20 ppb) rapidly afterwards coinciding with the disappearance of residues in stream water indicating that the uptake and bioconcentration potential by the insects for aminocarb were not high. Further work is necessary to confirm this observation since Penny (16) reported that the other insecticide, fenitrothion, is readily bioaccumulated by aquatic insects yielding a concentration factor of about 60.

Bioaccumulatlon of some pesticides (fenitrothion, aminocarb, permethrin) with real or potential application in forestry in Canada has been examined in laboratory experiments using larval rainbow trout and common duckweed. Bioaccumulation of an aromatic hydrocarbon, fluorene, has also been examined since some commercial formulations employ hydrocarbon solvents. Laboratory exposures of fish or plants were carried out by placing the organisms in dilute aqueous solutions of C labelled pesticide or hydrocarbon, and by measuring transfer of radioactivity from water to fish or plants. After transfer of fish or plants to untreated water, loss of radioactivity was measured similarly. These measures allowed calculation of uptake and depuration rate constants which were used to predict residue accumulations under various exposure conditions. Predicted residue accumulations agreed substantially with other predictive equations in the literature and with reported field observations. 

Chiron, S. and Barcelo, D., Determination of pesticides in drinking water by online solid-phase disk extraction followed by various liquid-chromatographic systems,/ Chromatogr., 645, 125-134, 1993. Sundaram, K. M. S. and Curry, J., High-performance liquid-chromatographic methods for the analysis of aminocarb, mexacarbate, and some of their At-methylcarhamate metabolites by postcolumn derivatization with fluorescence detection, J. Chromatogr. A, 672, 117-124, 1994. 

In the past, use has been made of Amberlite XAD-4 resin columns in the field for sample extraction of fenitrothion and aminocarb in rain water. The rain water was collected and extracted with the aid of a special sampling (collection) device equipped with Amberlite XAD-4 columns. It is possible that these types of extraction columns could have some field application in the extraction of large volumes of surface water for the determination of specific organic contaminants. However, one drawback associated with resin columns is the requirement of exhaustive cleaning with various solvents to remove all trace contaminants. Preparation of blanks, spiked blanks, spiked samples (in replicate), and sequential replicate sampling should be included as part of the specific QA/QCPs that are needed, if these Amberlite XAD-4 resin columns (or others) are used more extensively in the future. 

In addition to carboxylic acid derivatives, anhydrides and acid fluorides are also accessible straightforward via carbonylation reactions depending on the various nucleophiles used. Eor example, water (hydroxycarbonylation) will give carboxylic acid, alcohols (alkoxycarbonylation) will give esters, amines (aminocarb-onylation) will give amides, and anhydrides and acid fluorides can be produced if... 

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