Mancozeb

PHOTOACOUSTIC-FTIR DETERMINATION OF MANCOZEB IN PESTICIDE FORMULATIONS... 

Mancozeb is a dithiocarbamate pesticide with a very low solubility in organic and inorganic solvent. In this work we have developed a solvent free, accurate and fast photoacoustic FTIR-based methodology for Mancozeb determination in commercial fungicides. The proposed procedure was based on the direct measurement of the solid samples in the middle infrared region using a photoacoustic detector. A multivariate calibration approach based on the use of partial least squares (PLS) was employed to determine the pesticide content in commercially available formulations. 

The PLS calibration set was built mixing in an agate mortar different amounts of Mancozeb standard with kaolin, a coadjuvant usually formulated in agrochemicals. Cluster analysis was employed for sample classification and to select the adequate PLS model acording with the characteristics of the sample matrix and the presence of other components. 

The proposed PAS-FTIR procedure allows the determination of 30 samples h does not require any sample pre-treatment and avoids waste generation. So, it can conclude that the PAS-FTIR methodology is a reliable alternative to long and tedious classical method of analysis of Mancozeb and improves the sample frequency achieved by the FTIR procedure based on the measurement of KBr disks using internal standard. 

Khan PK, Sinha SP. 1996. Ameliorating effect of vitamin C on murine sperm toxicity induced by three pesticides (endosulfan, phosphamidon and mancozeb). Mutagenesis ll(l) 33-36. 

Representative products of this group are mancozeb, nabam, maneb, and zineb. Their chemical names, formulas, and physical-chemical properties are summarized below. 

High-performance liquid chromatography (HPLC) with a micellar mobile phase or with a selective pre-column or reaction detection system has also been used to determine alkylenebis(dithiocarbamaes). ° Zineb and mancozeb residues in feed were determined by ion-pair HPLC with ultraviolet (UV) detection at 272 nm. These compounds were converted to water-soluble sodium salts with ethylenediaminetetra-acetic acid (EDTA) and sodium hydroxide. The extracts were ion-pair methylated with tetrabuthylammonium hydrogensulfate (ion-pair reagent) in a chloroform-hexane solvent mixture at pH 6.5-8.S. The use of an electrochemical detector has also been reported. ... 

The limit of quantitation is 0.025 mg CS2kg which corresponds to 0.045 mg mancozeb kg ... 

Stock standard solution containing 1 mg mL mancozeb. Dissolve about 13.5 mg of mancozeb (taking into consideration the purity of the standard, which is about 74%) in 10 mL of 10% EDTA solution. Prepare this stock solution daily. Prepare working standard solutions by diluting appropriate volumes of the stock solution with 10% EDTA in order to obtain concentrations between 2.5 and 50 qg mL mancozeb. 

Dithiocarbamates are chemically characterized by the presence of metals in the molecule (iron, manganese, zinc, etc.) therefore, the measurement of these metals in urine has been proposed as an alternative approach to monitor exposure. For instance, increased urinary excretion of manganese has been reported in workers exposed to mancozeb (Canossa et al., 1993). Available data are at present insufficient to confirm the possibility of using metals as biomarkers of human exposure to DTC. 

Colosio, C., Barcellini, W., Maroni, M. et al. (1996) Immunomodulatory effects of occupational exposure to mancozeb, Archives of Environmental Health, 51(6) 445M51. 

Fungicides Benomyl Hexachlorobenzene Mancozeb Mefiram-complex Tributyltin Zineb Ziram... 

Ethylene thiourea, see Ferbam. Mancozeb. Maneb. Thiram... 

Ethylene thiram disulfide, see Thiram Ethylene thiuram disulfide, see Ferbam. Mancozeb Ethylene thiuram monosulfide, see Ferbam. Mancozeb. Maneb... 

Hypochlorous acid, see Carbon tetrachloride, 1,3-Dichloro-5,5-dimethylhydantoin, Phenol 5 Imidazoledthiocarboxylic acid, see Mancozeb... 

Heptane. Mancozeb. Maneb. Nitrobenzene, Thiram Sulfur dioxide, see Aldicarb. Carbon disulfide, p-Endosulfan, Methyl mercaptan, Methyl sulfide. Phorate... 

ChemicaPPhysical Hwang et al. (2003) studied the chemical oxidation of mancozeb (100 ppm) in aqueous solution using ozone (continuously supplied at a concentration of 3 ppm) and chlorine dioxide (20 ppm). Ozonation of the solution for 60 min yielded several degradation compounds including ethylene thiourea as the major product. Degradation of mancozeb by chlorine dioxide also yielded ethylene thiourea. After 60 min of treatment, mancozeb was still detected suggesting that chlorine dioxide was less effective as an oxidant than ozone. However, the investigators... 

Decomposes in acids releasing carbon disulfide. In oxygenated waters, mancozeb degraded to ethylene thiuram monosulfide, ethylene diisocyanate, ethylene thiourea, ethylenediamine, and sulfur (Worthing and fiance, 1991). 

Hwang, E. S., Cash. J.N., and Zabik, M.J. Determination of degradation products and pathways of mancozeb and ethylene-thionrea (ETU) in solutions due to ozone and chlorine dioxide treatments. J. Agric. FoodChem., 51(5) 1341-1346, 2003. 

Mancozeb, Maneb, Polyram and Dithane in soil and water samples were analyzed using the head space procedure for screening food samples for dithiocarbamate pesticide residues as described by McLeod and McCully W. 

Another well-known example within the pesticide area is the group ADI of 0-0.03 mg/kg bw/day allocated to dithiocarbamate fungicides. Thus, the Joint FAO/WHO Meeting on Pesticide Residues (JMPR) in 1993, in its evaluation of mancozeb, concluded that... 

Can a compound like mancozeb be used as a systemic fungicide ... 

No. Mancozeb is a broad-spectrum fungicide used as a protectant in many economically important crops but, because of its behaviour as a general cell toxicant, its conversion into a systemic would result in an unacceptable piiytotoxic crop response. 

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