Head Space Gas Procedure for Screening Food Samples for Dithiocarbamate Pesticide Residues

screening procedure has been developed for dithiocarbamate residues in foods. The CS2 evolved from an H2SO4-sample mixture at 60°C for 30 min was determined by GLC; recoveries of ferbam, thiram, and ziram added to apples, strawberries, lettuce, celery, cabbage, cucumber, and carrots ranged from 80 to 114% at 3.5 ppm and from 86 to 112% at 7 ppm. Recoveries of maneb, nabam, and zineb were not satisfactory. When an HCl-stannous chloride reagent was substituted for the H2SO4 reagent, recoveries of the ethylenebisdithiocarbamates were considerably improved. Maneb and ziram recoveries ranged from 70 to 95% in all samples; ferbam, thiram, and ziram, from 84 to 100%; and nabam, from 44 to 83%. The difference between duplicate recovery values, using the latter reagent, ranged from 0 to 11.2% units; 87% of these values were less than 10%.

STUDIES ON THE DISTRIBUTION OF MOLYBDENUM IN BIOLOGICAL MATERIAL: I. A SPECTROGRAPHIC STUDY OF THE OCCURRENCE OF MOLYBDENUM IN PLANTS GROWN IN THE PROVINCE OF QUEBEC

Molybdenum, identified spectrographically by the lines 3902.9Å, 3864.1Å, 3798.3Å, 3193.9Å, 3170.3Å, 3158.1Å and 3132.6Å, was found to be present in vetch, alfalfa, alsike, red clover, timothy, goldenrod, reed canary grass, field corn stalks, Canada thistle, ragweed, celery, beets and carrots grown on a farm in Jacques Cartier county, Quebec. Molybdenum could not be detected in the soil on which the plants grew.Molybdenum was not found in vetch plants grown on several farms in Brome, Compton and Sherbrooke counties; nor in timothy, alsike clover or red clover grown on a farm in Brome county; nor in lettuce, celery, cabbage, beets and carrots grown on two different muck soils of the St. Lawrence River valley, in Huntingdon county.The farm in Jacques Carder county lies in the Ottawa River valley drainage basin, the other farms do not. Known deposits of molybdenum occur in the Ottawa River valley.