Surveys of inorganic bromide ion residues in tomatoes, cucumbers and selfblanching celery, commercially produced in England following soil sterilisation with bromomethane, have been carried out since 1979. The mean bromide ion level in 29 late‐season cucumber samples was approximately 28 mg kg−1 and ranged up to 109 mg kg−1. Analysis of 242 tomato samples gave estimated mean bromide ion levels per plant ranging from 6 to 187 mg kg−1 in fruit picked throughout the season from seven holdings, on six of which bromomethane had been used fairly recently prior to planting. A statistically significant fall in bromide levels over the growing season was shown on four of the sites. In 38 samples of self‐blanching celery, the mean bromide ion level was 104 mg kg−1 even though the mean interval between fumigation and planting was in excess of 1 year. Retail surveillance indicated that a large number of crops are likely to have bromide ion levels below 10mg kg−1.
Surveys of lettuce, produced commercially in England and Wales, were carried out during the years 1977–82 to determine residues of inorganic bromide ion, following soil sterilisation with bromomethane. Lettuce grown on unfumigated soil contained less than 10 mg bromide ion kg−1, while most lettuce grown on bromomethane‐fumigated soil were found to contain higher levels of bromide ion, with a proportion in excess of 1000 mg kg−1. The accumulation of bromide ion appeared to be related to the interval between soil fumigation and planting, and also to the frequency of bromomethane application to the soil. A limited amount of data is presented on the levels of bromide ion in imported lettuce.
Lactating cows fed 0.05 part/million aldrin, 0.2 part/million y-BHC and 2.0 parts/million pp'-DDT in their concentrate ration gave detectable residues of dieldrin, y-BHC, pp'-DDE, pp'-TDE and pp'-DDT in the milk and also aldrin in the butter and cheese. The levels found after 28 days of feeding were not significantly greater than those after 14 days. Subsequent increase of the pesticide content of the feed increased the residue content of the milk, butter and cheese. Only a small percentage of pesticide residue was found in the buttermilk, separated milk and the whey.
The AOAC, de Faubert Maunder et al., and Wood methods have been examined for determining BHC, aldrin, heptachlor, DDT, and their major metabolites in milk, butter, cheese, and eggs. Also, the AOAC and the Laboratory of the Government Chemist (UK) methods have been investigated for these pesticides in apples, and both of the latter methods, together with a current EEC method, have been evaluated for measuring the pesticides in potatoes, carrots, and cabbages. Recoveries for these methods were determined by using samples with both added and incurred pesticide residues. There were no gross discrepancies in the results obtained by the different methods, although for certain foodstuffs and in certain situations some methods appeared preferable to others.
The widespread use of methyl bromide as a soil fumigant has necessitated the development of convenient and specific analytical methods for determining bromide/total bromine in foodstuffs and soils subsequent to fumigation. The gas-chromatographic method described by Heuser and Scudamore was initially adopted by this laboratory. However, for the substrates under investigation, i.e., salad crops and soils, we found that the method lacked resolution and reproducibility and was hindered by tailing and long retentiontime peaks.The modified method, for dried ground substrates, is described. Mass spectrometry was used on a non-routine basis to identify the chromatogram peaks. The mean recovery for dried vegetable substrates is 97% for a wide range of bromide levels, equivalent to approximately 20-1 000 mg kg-1 on a fresh mass basis. The method can be used to determine bromide down to 0.1 mg kg-l of substrate fresh mass.The method proved suitable as a basis for development.Keywords : Gas chromatographymass spectrometry ; bromide/total bromine determination ; 2-bromoethanol ; foodstufls ; soils
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