Pesticides methiocarb

Data on the DFR of chlorothalonil on carnation crops in previous studies indicated an increase in DFR of 10 to 20% with solvent extraction (unpublished data). However, in all of the current experiments, no differences were observed between dislodgeable foliar residue and solvent-extracted foliar residue for the pesticides methiocarb and thiophanate-methyl. 

Buronfosse, T, Moroni, R, Benoit, E., and Riviere, J. L. (1995), Stereoselective sulfoxidation of the pesticide methiocarb by flavin-containing monooxygenase and cytochrome P450-dependent monooxygenases of rat liver microsomes. Anticholinesterase activity of the two sulfoxide enantiomer. J. Biochem. Toxicol. 10, 179-189. 

Half-lives of two pesticides were estimated using the assumption that the decay was a first-order process. Half-lives were 28 8.5 days and 12 3.4 days for thiophanate-methyl and methiocarb, respectively. Crop volume was not a significant determinant of exposure using a grid count method. This was probably due to a large variation in the results with this method. 

Three pesticides having large variation in recommended dose rate were selected for this study. All were considered chemically stable and non-volatile. Model pesticides that were selected were thiophanate-methyl (CAS 23564-05-08 tradename Topsin M 500 g a.i./L), methiocarb (CAS 2032-65-... 

Half-life estimates of approximately 28 days for thiophanate-methyl indicate a very slow decay compared to methiocarb with an estimate of half-life of about 11 days. The application of a model based on a first-order decay process resulted in fairly high R2 and significant fit. The results suggest that both pesticides are relatively stable compared to other compounds under similar environmental conditions (Brouwer et al., 1994). With respect to the objectives of the study and the proposed model, it can be stated that the results confirm the assumption of a linear relationship between application rate (for both application techniques) and the increase of dislodgeable foliar residue. This relationship holds for modeling purposes. The contribution of the crop density or total crop surface area to the process of interception cannot be quantified with the results of the present study. Because the interception factor ranges from about 0.35 to 0.9 (Willis and McDowell, 1987), the... 

The pesticide rotenone and five other rotenoids were determined in formulations by using RPC (597, 598). The assay of warfarin in rodenti-cide preparations has been reported by Billings et al. (599). Methiocarb (3,5-dimethyl-4-(methylthio)phenylmethylcarbamate) has been determined in commercial preparations (666). The diaistereomers of sumicidin. 

Since their commercial introduction in the early 1960s,. V-methyIcarhamate pesticides (carbaryl, carbofuran (CF), methiocarb, etc.) have been used worldwide as substitutes for OCs because of their excellent efficiency as insecticides and nematicides, their relatively low mammalian toxicities in... 

A method for analysis of polar pesticides in wine by the use of automated in-tube SPME coupled with LC/ESI-MS was proposed (Wu et al., 2002). In-tube SPME is a microextraction and preconcentration technique that can be coupled on-line with high-performance liquid chromatography (HPLC), suitable for the analysis of less volatile and/ or thermally labile compounds. This technique uses a coated open tubular capillary as an SPME device and automated extraction. Using a polypyrrole coating, six phenylurea pesticides (diuron, fluometuron, linuron, monuron, neburon, siduron) and six carbamates (barban, car-baryl, chlorpropham, methiocarb, promecarb, propham) were analyzed in wine. Structures of compounds are reported in Fig. 9.4. Due to the high extraction efficiency of the fiber toward polar compounds, benzene compounds, and anionic species, LODs ranging between 0.01 and 1.2pg/L were achieved, even if the sample ethanol content affects the recoveries of analytes. 

Figure 9.4. Phenylurea pesticides and carbamates detected in wine by automated intube SPME and LC/ESI-MS analysis (Wu et al., 2002). (14) monuron, (15) fluome-turon, (16) siduron, (17) diuron, (18) linuron, (19) neburon, (20) propham, (21) chlorpropham, (22) barban, (23) promecarb (structures of carbaryl and methiocarb are reported in Figs. 9.1 and 9.11, respectively).

The U.S.A., through the National Pesticide Survey, " which was organized by the Environmental Protection Agency (US-EPA), established a fist of compounds based on the amount used (>7000 Tons), water solubility (>30 mg/1), and hydrolysis half-life (>25 weeks). The list includes some carbamate pesticides (e.g., aldicarb, propoxur, carbaryl, carbofuran, methiocarb, methomyl, oxamyl, cycloate, butylate, propham, and swep) and various derivatives (e.g., aldicarb sulphone, aldicarb sulphoxide, and 3-hidroxycarbofiiran). In Europe, a list of priority pollutants including pesticides was established in order to protect the environment from the adverse ecological impact of these compounds. ... 

Hofineistcr, M. V.. and Boncfeld-Jorgen.scn, E. C. (2004). Effects of the pesticides prochloraz and methiocarb on human estrogen receptor ot and ji mRNA levefs analyzed by on-line RT-PCR. Toxicol, in Vitro 18,427-433. 

The use of different eluents in LC-RP separations was examined to optimize LC separation and determination of carbamates besides other pesticides by TSP-LC-MS [244]. The effects of additives on LC separation and of the vaporizer temperature on ion formation in TSP-FIA-MS analysis were studied for N-methylcarba-mate [252], carbamates [242] and (thio)carbamates [242] pesticides. A strong reduction in abundance of the characteristic ions [M-tH-CHjNCOj and [M-H-CH3NC0] for methiocarb and its sulone were found because of thermal degradation at 90 °C which made quantitation difficult [252]. The addition of trialkylammo-nium formates increased selectivity and sensitivity, detection limits being < 20 ng in full scan mode [242]. 

FIGURE 13.5 UHPLC—MS/MS separation of an apple extract, fortified with 17 polar pesticides. Peak identification (1) carbendazim, (2) thiabendazole, (3) carbofuran, (4) carbaryl, (5) linuron, (6) methiocarb, (7) epoxiconazole, (8) flusilazole, (9) diflubenzuron, (10) tebuconazole, (11) imazalil, (12) propiconazole, (13) trUlumuron, (14) bitertanol, (15) prochloraz, (16) teflubenzuron, (17) flufenoxuron. Source From Reference 181], reproduced by permission of Elsevier. 

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