The Stability of Mancozeb in the Six Mixtures and the Level of ETU

Identification of some degradation products is described by HPLC and capillary gas chromatography mass spectrometry in methanol extract of mancozeb 70 WP after storing 5 years in the laboratory Through analyzing and comparing the obtained mass spectra with the standard mass spectra could identify the degradation products and then determine the proposed degradation pathways The results showed that the degradation products and pathways were very similar to other ethylenebisdithiocarbamate fungicides The degradation products of mancozeb detected in the formulation include ETU, EU(2 imidazolidinone) and EDI(ethylenediisothiocyanat e) Mancozeb is degraded primarily by oxidative reaction The stability of mancozeb and the level of ETU were detected via the xanthated method and HPLC-UV in mancozeb and its mixtures ( mancozeb+ fosethyl Al, mancozeb+chlorothalonil, mancozeb+metalaxyl,mancozeb+carbendazim,mancozeb+triadimefon,mancozeb+dimethachion) by CIPAC MT46 The relative rate of decomposition of mancozeb was 9 3%～14 3% The level of ETU was 3 9% for 2 years,6 9% for 5 years in the formulation Fosethyl Al, carbendazim and triadimefon may enhance stabil ity of mancozeb by heating Except mancozeb+dimethachlon,the levels of ETU in five mixtures were 1 91%～3 11% after storing 2 years Fosethyl Al may significantly reduce formation of ETU in mancozeb formulation