Detecting mycotoxins in agricultural commodities |
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Authors: | Whitaker Thomas B |
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Institution: | (1) USDA/ARS, North Carolina State University, Box 7625, 27695-7625 Raleigh, NC |
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Abstract: | It is difficult to obtain precise and accurate estimates of the true mycotoxin concentration of a bulk lot when using a mycotoxin-sampling
plan that measures the concentration in a small portion of the bulk lot. A mycotoxin-sampling plan is defined by a mycotoxin
test procedure and a defined accept/reject limit. A mycotoxin test procedure is a complicated process and generally consists
of several steps: (a) a sample is taken from the lot, (b) the sample is ground (comminuted) in a mill to reduce particle size,
(c) a subsample is removed from the comminuted sample, and (d) the mycotoxin is extracted from the comminuted subsample and
quantified. Even when using accepted test procedures, there is variability associated with each step of the mycotoxin test
procedure. Because of this variability, the true mycotoxin concentration in the lot cannot be determined with 100% certainty
by measuring the mycotoxin concentration in a sample taken from the lot. The variability for each step of the mycotoxin test
procedure, as measured by the variance statistic, is shown to increase with mycotoxin concentration. Sampling is usually the
largest source of variability associated with the mycotoxin test procedure. Sampling variability is large because a small
percentage of kernels are contaminated and the level of contamination on a single seed can be very large. Methods to reduce
sampling, sample preparation, and analytical variability are discussed. |
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Keywords: | Sampling mycotoxins sampling variability sample preparation variability analytical variability buyer’ s risk false negatives seller’ s risk false positives operating characteristic curve sampling plan performance |
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