METHOD VALIDATION OF DITHIOCARBAMATES RESIDUES ON SOME EGYPTIAN COMMODITIES USING GC-MASS INSTRUMENT

Dithiocarbamates are a non systemic group of fungicides widely used to protect crops from fungal diseases. an applicable gc-mass method is found to be specified to determine the residues of dithiocarbamates. the current methodology used to determine dithiocarbamates group (maneb, mancozeb, metiram, propineb, thiram, zineb) involves the analysis of carbon disulphide (cs_2) generated after hydrolysis of the compound present in samples. the method performance was tested using recovery tests on different types of matrices (fresh fruits, vegetables and water samples). the average recoveries of cs_2 at different concentration levels of cs_2 varied between 70-120 %. the limit of quantitation is 0.05 ppm. the method showed to be linear up to 0.5 ppm. the reproducibility expressed as relative standard deviation was less than 12%. the measurement uncertainty in terms of expanded uncertainty and expressed as relative standard deviation (at 95 % confidence level and coverage factor of k = 2) is in the range of ± 24 %. a total of 71 samples of selected commodities (green beans, green peas, green brocclli, green onion, potato leaves, peanut and water) were analyzed to assess levels of dithiocarbamates during the period of january to december 2010 taken from different markets of egypt.