Random Variation

  • Thomas B. Whitaker
  • Andrew B. Slate
  • M. Bruno Doko
  • Britt M. Maestroni
  • Andrew Cannavan


Even when using accepted sampling, sample preparation, and analytical procedures (Campbell et al. 1986; Malone 2000; Dickens and Satterwhite 1969; Association of Official Analytical Chemists 1990; Nesheim 1979; Steyn et al. 1991), there are errors (the term error will be used to denote variability) associated with each of the steps of the mycotoxin test procedure (Whitaker et al. 1972, 1974, 1976, 1979, 1993, 1998; Dickens et al. 1979; Remington and Schrok 1970; Schatzki 1995a, b). Because of these errors, the true mycotoxin concentration in the lot cannot be determined with 100% certainty by measuring the mycotoxin concentration in a test portion taken from a laboratory sample taken from the lot. For example, 10 replicated aflatoxin test results from each of six contaminated shelled peanut lots are shown in Table 8.1 (Whitaker et al. 1972). For each test result in the table, the mycotoxin test procedure consisted of (a) comminuting a 5.45-kg laboratory sample of peanut kernels in a USDA subsampling mill developed by Dickens and Satterwhite (1969), (b) removing a 280-g test portion from the comminuted laboratory sample, (c) solvent extracting aflatoxins from a 280-g test portion as described by AOAC Method II (Association of Official Analytical Chemists 1990), and (d) quantifying the aflatoxins densitometrically using thin layer chromatography (TLC). The 10 aflatoxin test results from each lot are ranked from low to high to demonstrate several important characteristics about replicated aflatoxin test results taken from the same contaminated lot.


High Performance Liquid Chromatography Total Variability Laboratory Sample Official Analytical Chemist Test Portion 
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Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  • Thomas B. Whitaker
    • 1
  • Andrew B. Slate
    • 2
  • M. Bruno Doko
    • 3
  • Britt M. Maestroni
    • 3
  • Andrew Cannavan
    • 3
  1. 1.US Department of Agriculture Agricultural Research ServiceNorth Carolina State UniversityRaleighUSA
  2. 2.Biological and Agricultural Engineering DepartmentNorth Carolina State UniversityRaleighUSA
  3. 3.Food and Environmental Protection Laboratory Joint FAO/IAEA Division of Nuclear Techniques in Food and AgricultureInternational Atomic Energy Agency (IAEA)ViennaAustria

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