Propachlor

Health advisories have been issued (269) for diphenamid, metolachlor, pronamide, and propachlor. Other acid amide herbicides include butachlor [23184-66-9] and ethalfluralin [55283-68-6],... 

R F Handmade Paints Inc., 245 R.S.A. Coi"poration, 246 RAG Group AG, 165 RAIMONT , phosphoric acid, 114 Raisio Chemicals Ltd., 156 Rajsliree Agro Chem, 174 Rallis hidia Ltd., 175 RAMROD , propachlor, 114 RANEY , catalysts, 114 RAPICHLENE , methylene chloride, 114 Rasa Industries Ltd., 187 Raschig GmbH, 165... 

Martin M, E Eerrer, R Alonso, J Eernandez (1995) Bioremediation of soil contaminated by propachlor using native bacteria. Int Biodet Biodeg 213-225. 

Chloroacetanilides are soil-applied herbicides used for pre- and early post-emergence control of annual grasses and broadleaf weeds in crops. Representative chloroacetanilide compounds, alachlor, acetochlor, and metolachlor, are extensively used worldwide. Other chloroacetanilides with limited usages include propachlor, bu-tachlor, metazachlor, pretilachlor, and thenylchlor. Public environmental concerns and government regulatory requirements continue to prompt the need for reliable methods to determine residues of these herbicides. There now exist a variety of analytical methods to determine residues of these compounds in crops, animal products, soil, and water. The chemical structures and major crops in which these compounds are used are summarized in Table 1. 

The focus of this article is to describe the residue methodologies for alachlor, acetochlor, metolachlor, and propachlor. Four residue analytical methods are discussed ... 

The current methodology to determine residues of alachlor, acetochlor, propachlor, and butachlor in crops and animal products was developed over the last two decades by researchers at the Monsanto Company. These herbicides degrade rapidly in plants and animals to numerous metabolites that can be hydrolyzed to common aniline moieties. Little to no parent herbicide is found as intact residue in crops and animal products therefore, the residue methodology focuses on the determination of the common moieties that are derived from the parent herbicides and their metabolites. Initially, gas chromatography (GC) with flame ionization detection, nitrogen-phosphorus... 

The complexity of the metabolism of alachlor, acetochlor, butachlor, and propachlor has led to the development of degradation methods capable of hydrolyzing the crop and animal product residues to readily quantitated degradation products. Alachlor and acetochlor metabolites can be hydrolyzed to two major classes of hydrolysis products, one which contains aniline with unsubstituted alkyl groups at the 2- and 6-positions, and the other which contains aniline with hydroxylation in the ring-attached ethyl group. For alachlor and acetochlor, the nonhydroxylated metabolites are hydrolyzed in base to 2,6-diethylaniline (DBA) and 2-ethyl-6-methylaniline (EMA), respectively, and hy-droxylated metabolites are hydrolyzed in base to 2-ethyl-6-(l-hydroxyethyl)aniline (HEEA) and 2-(l-hydroxyethyl)-6-methylaniline (HEMA), respectively. Butachlor is metabolized primarily to nonhydroxylated metabolites, which are hydrolyzed to DEA. Propachlor metabolites are hydrolyzed mainly to A-isopropylaniline (NIPA). The base hydrolysis products for each parent herbicide are shown in Eigure 1. Limited interference studies have been conducted with other herbicides such as metolachlor to confirm that its residues are not hydrolyzed to the EMA under the conditions used to determine acetochlor residues. Nonhydroxylated metabolites of alachlor and butachlor are both hydrolyzed to the same aniline, DEA, but these herbicides are not used on the same crops. 

Residues of alachlor and acetochlor are determined by similar methods involving extraction, hydrolysis to the common aniline moieties, and separation and quantitation by reversed-phase FIPLC with electrochemical detection. The analytical method for acetochlor is included as a representative method for residue determination of alachlor and acetochlor in plant and animal commodities. Propachlor and butachlor residues, both parent and metabolite, are determined by similar analytical methods involving extraction, hydrolysis to common aniline moieties, and separation and quantitation by capillary GC. The analytical method for propachlor is included as a representative method. The details of the analytical methods for acetochlor and propachlor are presented in Sections 4 and 5, respectively. Confirmation of the residue in a crop or... 

Propachlor, alachlor, acetochlor, and butachlor degrade readily and extensively in soil mainly through displacement of chlorine followed by further metabolism to numerous... 

Analytical method for the determination of propachlor and its metabolites in plants and animals... 

Propachlor is extracted from plant and animal material with aqueous acetonitrile. After filtration and evaporation of the solvent, the extracted residue is hydrolyzed with base, and the hydrolysis product, NIPA, is steam distilled into dilute acid. The acid distillate is partitioned with dichloromethane. The aqueous layer is adjusted to a basic pH, and NIPA is extracted with isooctane. The extracted residues are cleaned up using a silica SPE column, and NIPA is eluted with isooctane-ethyl acetate (9 1, v/v) solvent mixture. Quantitation is by GC/NPD. 

Weigh 0.1 g in propachlor equivalents of the representative NIPA-producing metabolite into a 100-mL volumetric flask. Dilute the standard to volume with absolute ethanol, and mix the solution well to ensure complete dissolution. This solution contains 1000 qg mL propachlor equivalents of NIPA-producing metabolite. Dilute this solution as appropriate to prepare fortiflcation standards at the following concentrations 0.10,0.50,1.0,2.0,5.0,25, and 50-qg mL Store all standards refrigerated (0-6 °C) in amber-glass bottles. 

The amount of the analyte determined is converted to the equivalent amount of propachlor for reporting purposes. This is readily accomplished using the following... 

The conversion factor, 1.57, corrects for the difference in the molecular weight between propachlor (211.69) and NIPA (135.21). 

The method was validated in numerous matrices, both animal and crop, at levels ranging from 0.01 to lOmgkg" in propachlor equivalents. Analytical recoveries were >70%. No apparent trends were observed for either the level of fortification or the matrix analyzed. 

The LOD and LOQ were statistically calculated using the data obtained by spiking each matrix (milk, egg, animal tissues, and corn and sorghum raw agricultural commodities) with 0.02mgkg propachlor equivalents. The method s LOD and LOQ for the NIPA were 0.005 and 0.015 mg kg respectively, for both crop and animal tissues. Some fortified matrices had acceptable recoveries at levels below the LOQ. The LLMV was 0.01 and 0.02mgkg for crop and animal commodities, respectively. The LLMV is defined as the lowest fortification level at which acceptable NIPA recovery and precision were demonstrated. 

Martin M, Mengs G, Plaza E, Garbi C, Sanchez M, Gibello A, Gutierrez F, Ferrer E (2000) Propachlor removal by Pseudomonas strain GCHII in an immobilized cell system. Appl Env Microbiol 66 1190-1194... 

The most important substituted anilide herbicides (Fig. 10, Table 3) are Propanil,Propachlor,and Alachlor [43,151,175-178]. 

Propachlor [1918-16-7] Daphnla magna EC50 (48-h) 0.84 Mayer and Ellersieck, 1986... 

Chlorinated dihydroxybenzenes, see Pentachlorophenol Chlorine, see Allidochlor. Anilazine. Bromacil. Chlordane, 2,4-D, Dalapon-sodium. p.p -DDT, Dicamba. Dieldrin, Diuron, Malathion, Monuron. Pentachloronitrobenzene. Picloram. Propachlor. 

Isocyanatopropane, see Atrazine Isofenphos oxon, see Isofenphos Isoheptane, see PCB-1242 Isohexane, see PCB-1242 Isononane, see PCB-1242 Isononanes, see Octane Isooctane, see PCB-1242 Isooctanes, see Octane Isophthalic acid, see ro-Xylene Isopropoxyphenol, see ProDoxnr Isopropyl alcohol, see Isopropyl acetate Isopropylatnide, see Bentazone IV-Isopropylaniline, see Propachlor Isopropylbenzene, see Propylbenzene, PCB-1242,... 

IV-Isopropyl-3-hydroxyoxindole, see Propachlor 2,3-Isopropylidenedioxyphenol, see Bendiocarb Ispropylisocyanate, see Iprodione 2 Isopropyl-4-methyl-6-hydroxypyrimidine, see Diazinon... 

Isopropyl-6-methylpyrimidin-4-ol, see Diazinon iV-Isopropyloxindole, see Propachlor Isopropyl salicylate, see Isofenphos... 

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