Sampling Almonds for Aflatoxin, Part I: Estimation of Uncertainty Associated with Sampling, Sample Preparation, and Analysis

• Published in: Journal of AOAC International Vol. 89; no. 4; pp. 1027 - 1034
• Main Authors: Whitaker, T.B, Slate, A.B, Jacobs, M, Hurley, J.M, Giesbrecht, F.G
• Format: Journal Article
• Language: English
• Published: Gaithersburg, MD AOAC International 01-07-2006; Oxford University Press
• Subjects: aflatoxin B1; Aflatoxin B1 - analysis; Aflatoxins; Aflatoxins - analysis; Almond; almonds; Analysis of Variance; Biological and medical sciences; Chemistry Techniques, Analytical - methods; Chromatography, High Pressure Liquid - methods; Evaluation Studies as Topic; Food; Food Analysis - methods; food contamination; Food industries; Food toxicology; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; Identification and classification; maximum residue limits; Measurement; methodology; Methods; microbial detection; Prunus; Prunus - metabolism; Regression Analysis; Reproducibility of Results; Research Design; reversed-phase high performance liquid chromatography; safety testing; Sample Size; secondary metabolites; shelling; Statistical sampling; Testing; toxigenic strains; United States; Uncertainty; Nuts; Estimation; Prunus dulcis; Mycotoxin; Rosaceae; Samplings; Toxin; Almond; Sample preparation; Dicotyledones; Angiospermae; Spermatophyta; Sampling; Aflatoxin
• DOI: 10.1093/jaoac/89.4.1027
• EISSN: 1944-7922
• ISSN: 1060-3271

Domestic and international regulatory limits have been established for aflatoxin in almonds and other tree nuts. It is difficult to obtain an accurate and precise estimate of the true aflatoxin concentration in a bulk lot because of the uncertainty associated with the sampling, sample preparation, and analytical steps of the aflatoxin test procedure. To evaluate the performance of aflatoxin sampling plans, the uncertainty associated with sampling lots of shelled almonds for aflatoxin was investigated. Twenty lots of shelled almonds were sampled for aflatoxin contamination. The total variance associated with measuring B1 and total aflatoxins in bulk almond lots was estimated and partitioned into sampling, sample preparation, and analytical variance components. All variances were found to increase with an increase in aflatoxin concentration (both B1 and total). By using regression analysis, mathematical expressions were developed to predict the relationship between each variance component (total, sampling, sample preparation, and analysis variances) and aflatoxin concentration. Variance estimates were the same for B1 and total aflatoxins. The mathematical relationships can be used to estimate each variance for a given sample size, subsample size, and number of analyses other than that measured in the study. When a lot with total aflatoxins at 15 ng/g was tested by using a 10 kg sample, a vertical cutter mixer type of mill, a 100 g subsample, and high-performance liquid chromatography analysis, the sampling, sample preparation, analytical, and total variances (coefficient of variation, CV) were 394.7 (CV, 132.4%), 14.7 (CV, 25.5%), 0.8 (CV, 6.1%), and 410.2 (CV, 135.0%), respectively. The percentages of the total variance associated with sampling, sample preparation, and analytical steps were 96.2, 3.6, and 0.2, respectively.