Johansson A S, Whitaker T B, Hagler W M, Giesbrecht F G, Young J H, Bowman D T
US Department of Agriculture, Agricultural Research Service, North Carolina State University, Raleigh 27695-7625, USA.
J AOAC Int. 2000 Sep-Oct;83(5):1264-9.
The variability associated with testing lots of shelled corn for aflatoxin was investigated. Eighteen lots of shelled corn were tested for aflatoxin contamination. The total variance associated with testing shelled corn was estimated and partitioned into sampling, sample preparation, and analytical variances. All variances increased as aflatoxin concentration increased. With the use of regression analysis, mathematical expressions were developed to model the relationship between aflatoxin concentration and the total, sampling, sample preparation, and analytical variances. The expressions for these relationships were used to estimate the variance for any sample size, subsample size, and number of analyses for a specific aflatoxin concentration. Test results on a lot with 20 parts per billion aflatoxin using a 1.13 kg sample, a Romer mill, 50 g subsamples, and liquid chromatographic analysis showed that the total, sampling, sample preparation, and analytical variances were 274.9 (CV = 82.9%), 214.0 (CV = 73.1 %), 56.3 (CV = 37.5%), and 4.6 (CV = 10.7%), respectively. The percentage of the total variance for sampling, sample preparation, and analytical was 77.8, 20.5, and 1.7, respectively.
对大量带壳玉米进行黄曲霉毒素检测时的变异性进行了研究。对18批带壳玉米进行了黄曲霉毒素污染检测。估计了与带壳玉米检测相关的总方差，并将其划分为采样方差、样品制备方差和分析方差。所有方差均随黄曲霉毒素浓度的增加而增加。通过回归分析，建立了数学表达式来模拟黄曲霉毒素浓度与总方差、采样方差、样品制备方差和分析方差之间的关系。这些关系的表达式用于估计特定黄曲霉毒素浓度下任何样本量、子样本量和分析次数的方差。对一批黄曲霉毒素含量为十亿分之二十的样本进行检测，样本量为1.13千克，使用罗默磨，子样本量为50克，并采用液相色谱分析，结果表明总方差、采样方差、样品制备方差和分析方差分别为274.9（变异系数=82.9%）、214.0（变异系数=73.1%）、56.3（变异系数=37.5%）和4.6（变异系数=10.7%）。采样方差、样品制备方差和分析方差占总方差的百分比分别为77.8%、20.5%和1.7%。
