Aldicarb sulfoxide

With aldicarb, primary metabolic attack is again by oxidation and hydrolysis. Hydrolytic cleavage yields an oxime and represents a detoxication. Oxidation to aldicarb sulfoxide and sulfone, however, yields products that are active anticholinesterases. Carbofuran is detoxified by both hydrolytic and oxidative attack. 

In this study, the preliminary findings showed that the HPLC/fluorescence data were in agreement for all 12 carbamates with HPLC/ESI-MS/MS for most of the nine fruits and vegetables at the 1.0 ng g fortification level. The recoveries were generally within 70-120% however, at the 1.0 ng g level in each commodity, HPLC/ESI-MS (single-stage MS) had difficulty with interferences for three out of the 12 carbamate pesticides (aldicarb sulfoxide, aldicarb sulfone, and 3-hydroxycarbofuran), which made quantification impossible for these three compounds. 

Oxime carbamates are generally applied either directly to the tilled soil or sprayed on crops. One of the advantages of oxime carbamates is their short persistence on plants. They are readily degraded into their metabolites shortly after application. However, some of these metabolites have insecticidal properties even more potent than those of the parent compound. For example, the oxidative product of aldicarb is aldicarb sulfoxide, which is observed to be 10-20 times more active as a cholinesterase inhibitor than aldicarb. Other oxime carbamates (e.g., methomyl) have degradates which show no insecticidal activity, have low to negligible ecotoxicity and mammalian toxicity relative to the parent, and are normally nondetectable in crops. Therefore, the residue definition may include the parent oxime carbamate (e.g., methomyl) or parent and metabolites (e.g., aldicarb and its sulfoxide and sulfone metabolites). The tolerance or maximum residue limit (MRL) of pesticides on any food commodity is based on the highest residue concentration detected on mature crops at harvest or the LOQ of the method submitted for enforcement purposes if no detectable residues are found. For example, the tolerances of methomyl in US food commodities range from 0.1 to 6 mg kg for food items and up to 40 mg kg for feed items. ... 

Aldicarb nitrile, see Aldicarb Aldicarb nitrile sulfone, see Aldicarb Aldicarb nitrile sulfoxide, see Aldicarb Aldicarb oxime, see Aldicarb Aldicarb oxime sulfone, see Aldicarb Aldicarb oxime sulfoxide, see Aldicarb Aldicarb sulfone, see Aldicarb Aldicarb sulfone acid, see Aldicarb Aldicarb sulfone alcohol, see Aldicarb Aldicarb sulfone aldehyde, see Aldicarb Aldicarb sulfone amide, see Aldicarb Aldicarb sulfone oxime, see Aldicarb Aldicarb sulfoxide, see Aldicarb Aldicarb sulfoxide acid, see Aldicarb Aldicarb sulfoxide alcohol, see Aldicarb Aldicarb sulfoxide aldehyde, see Aldicarb Aldicarb sulfoxide amide, see Aldicarb Aldicarb sulfoxide nitrile, see Aldicarb Aldicarb sulfoxide oxime, see Aldicarb Aldrin, see Dieldrin Aldrin diol, see Aldrin Alkyl hydroperoxides, see Acetaldehyde Allyl alcohol, see Allyl chloride, l,2-Dibromo-3-chloropropane, 1,2-Dichloropropane Allylbenzene, see Isopropylbenzene p-(2-Atnino-3-nitrophenyl)glucopyranoside, see 2-Nitroaniline Allyl chloride, see Allyl alcohol, l,2-Dibromo-3-chloropropane, 1,2-Dichloropropane 2-Aminobenzimidazole, see Benomvl... 

Rajagopal et al. (1984) used numerous compounds to develop a proposed pathway of degradation of aldicarb in soil. These compounds included aldicarb oxime, A-hydroxymethyl aldicarb, A-hydroxymethyl aldicarb sulfoxide, A-demethyl aldicarb sulfoxide, A-demethyl aldicarb sulfone, aldicarb sulfoxide, aldicarb sulfone, A-hydroxymethyl aldicarb sulfone, aldicarb oxime sulfone, aldicarb sulfone aldehyde, aldicarb sulfone alcohol, aldicarb nitrile sulfone, aldicarb sulfone amide, aldicarb sulfone acid, aldicarb oxime sulfoxide, aldicarb sulfoxide aldehyde, aldicarb sulfoxide alcohol, aldicarb nitrile sulfoxide, aldicarb sulfoxide amide, aldicarb sulfoxide acid, elemental sulfur, carbon dioxide, and water. Mineralization was more rapid in aerobic surface soils than in either aerobic or anaerobic subsurface soils. In surface soils (30 cm depth) under aerobic conditions, half-lives ranged from 20 to 361 d. In subsurface soils (20 and 183 cm depths), half-lives under aerobic and anaerobic conditions were 131-233 and 223-1,130 d, respectively (Ou et al, 1985). The reported half-lives in soil ranged from approximately 70 d (Jury et ah, 1987) to several months (Jones et al, 1986). Bromilow et al. (1980) reported the half-life for aldicarb in soil to be 9.9 d at 15 °C and pH 6.34-7.0. 

Groundwater. In Florida groundwater, aldicarb was converted to aldicarb sulfoxide under aerobic conditions. Conversely, under anaerobic conditions (pH 7.7), oxidative metabolites (aldicarb sulfoxide and aldicarb sulfone) reverted back to the parent compound (aldicarb). Half-lives in unfiltered and filtered groundwater were 635 and 62 d, respectively (Miles and Delfino, 1985). In sterile anaerobic groundwater at pH 8.2, aldicarb slowly hydrolyzed to the aldicarb oxime. In a microorganism-enriched groundwater at pH 6.8, aldicarb rapidly degraded to... 

Aldicarb degrades rapidly in the chlorination of drinking water forming aldicarb sulfoxide which subsequently degrades to aldicarb sulfone, (chloromethyl)sulfonyl species and A-chloro-aldicarb sulfoxide (Miles, 1991). 

Hansen, J.L. and Spiegel, M.H. Hydrolysis studies of aldicarb, aldicarb sulfoxide and aldicarb sulfone. Environ. Toxicol. Chem., 2(2) 147-153, 1983. 

Miles, C.J. Degradation of aldicarb, aldicarb sulfoxide, and aldicarb sulfone in chlorinated water, Environ. Sci Technol, 25(10) 1774-1779, 1991. 

Base hydrolysis kinetic data are reported for ppb solutions of carbofuran,3-OH carbofuran, methomyl and oxamyl. The results are compared with those reported previously for aldicarb, aldlcarb sulfoxide, and aldicarb sulfone. Second order reaction rate constants, k, have been calculated and range from 169 liter mln mole for oxamyl to 1.15 liter mln mole for aldicarb. The order for rate of base hydrolysis is as follows oxamyl >3-hydroxycarbofuran >aldicarb sulfone v- carbofuran >aldicarb sulfoxide > methomyl -v aldicarb. The activation energy for the base hydrolysis of carbofuran was measured to be 15.1 +0.1 kcal mole , and is similar to the value previously reported for aldicarb sulfone. Rapid detoxification of aldicarb, a representative oxime carbamate pesticide, by in situ hydrolysis on reactive ion exchange beds is reported. 

These data were measured at or extrapolated to ambient temperature and pH values. The data are discussed in the text. NA = not available. b/ Kq = soil water distribution coefficient (K ) divided by the organic carbon content of the soil, cj Whenever possible, half-life for soil dissipation is derived from the field data half-lives described in the text rather than lab data. As such, it may not represent a true first-order process. Value has been estimated from the equation in ref. 20. e/ Hydrolysis of total residues (aldicarb + sulfoxide + sulfone). pK for p -phthalic acid is 3.5. The chlorine atoms of DCPA should lower the pK to about 2. Conditions optimized for soil metabolism. 

SS Yang, Y Smetena. Determination of aldicarb, aldicarb sulfoxide and aldicarb sulfone in tobacco using high-performance liquid chromatography with dual post-reaction and fluorescence detection. J Chromatogr A 664 289-294, 1994. 

JA Itak, Y Selisker, DP Herzog. Development and evaluation of a magnetic particle based enzyme immunoassay for aldicarb, aldicarb sulfone and aldicarb sulfoxide. Chemosphere 24 11-21, 1992. 

Lemley, A.T., Zhong, W.Z. (1983) Kinetics of aqueous base and acid hydrolysis of aldicarb, aldicarb sulfoxide and aldicarb sulfone. J. Environ. Sci. Health B18, 189-206. 

Chromatogram 6 is 0.30g of fat that was fortified with 80.6 yg aldicarb sulfoxide eluted with program B and detected by the sulfur mode. The polarity of the aldicarb sulfoxide has allowed it to be separated from interferences. 

Parathion to paraoxon 218X Phorate to phorate sulfoxide 6X Phorate to phorate sulfone 21X Aldicarb to aldicarb sulfoxide 76X Aldicarb to aldicarb sulfone 17X... 

Aldicarb sulfoxide Beans, French 1 N N Latin Amer. ... 

The oxidation of pesticide compounds usually generates products with aqueous mobilities that are either similar to or greater than that of the parent compound. The oxidation of aldicarb, for example, produces aldicarb sulfoxide and aldicarb sulfone, both of which have lower A/qc values than aldicarb (Moye and Miles, 1988). Similarly, because most phototransformations involve either the hydrolysis or oxidation of the parent compound, they yield products that are generally more polar (Mill and Mabey, 1985), and thus more water soluble than the parent compound. Reduction reactions, by contrast, may result in products that are less water soluble than their parent compound. Examples include the reduction of aldicarb sulfoxide to aldicarb (Miles and Delfino, 1985 Lightfoot et al, 1987) and the reduction of phorate sulfoxide to phorate (Coats, 1991). The reactivity of transformation products may be either higher or lower than that of their parent compounds. However, those in the former category (i.e., reactive intermediates) are, of course, much less likely to be detected in the hydrologic system than more stable products. 

---