Simple analysis method to measure phosphine residue in grains, herbs, and spices using headspace gas chromatography
2008
Misumi, T.(Japan. Ministry of Agriculture, Forestry and Fisheries, Yokohama. Yokohama Plant Protection Station) | Kitamura, H. | Oogita, T.
Trials were conducted to determine whether an analysis method for measuring phosphine residue using a headspace autosampler, which provides rapid analysis and easier handling, is equally applicable to herbs and spices and other kinds of grains as it is to wheat and small beans. For measuring residue levels, the optimal equilibrium time, best sample amount per vial, and impact of cracking a sample before fumigation were investigated using 17 kinds of grains, herbs, and spices: popcorn, dent corn, soybeans, black pepper, cumin seed, celery seed, fennel seed, white peony, huang qi, rosemary, turmeric, coriander seed, hemp seed, oregano, basil, mustard seed, and horseradish. Optimal sample amounts varied from 1 g to 5 g depending on the kind of sample. Large and dense samples required a long holding time (120 minutes), and small and low-density samples did not require a long holding time. The analysis method concerned could be applied to grains, herbs, and spices as a simple analysis method of measuring phosphine residue instead of absorption spectrophotometry at a 1 ppb level quantitative limit. However, grains, herbs, and spices with a larger grain size would often provide dispersive data, although this seems to depend on the kind of grain, herb, or spice. Homogenization of samples or increasing sample size by using a larger vial is appropriate to conduct accurate analysis. Fumigation of a sample in fractions or chip shapes which has been artificially cracked is inadequate to quantify phosphine residue because in turmeric, residual rates increased according to fraction size, and smaller laurel chips indicated a higher residue than larger ones.
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