Stahl G L, Kratzer D D, Kasson C W
Upjohn Co., Kalamazoo, MI 49001.
J Assoc Off Anal Chem. 1989 Mar-Apr;72(2):237-41.
A modification of the AOAC microbiological determination of neomycin in feeds was collaboratively studied by 12 laboratories. The official method was modified by substituting a constant salt concentration diluent for the feed extract diluent, preparing the agar medium in tris buffer, and performing the test with a monolayer plating system. Each laboratory performed single assays on 8 samples in a randomized sequence. The samples included duplicates of a cattle and swine feed at 2 different marketed concentrations. The mean recovery across all laboratories was 110.7% of theory with a range of means of 69.4-128.6 across the 12 laboratories. The results of one laboratory and 2 additional values from different laboratories were deemed outliers and excluded from statistical analysis. The statistical analysis gave a confidence interval of +/- 26% for individual assays.
12个实验室共同研究了对AOAC饲料中新生霉素微生物测定方法的一种改进。通过用恒定盐浓度稀释剂替代饲料提取物稀释剂、在三羟甲基氨基甲烷缓冲液中制备琼脂培养基以及使用单层平板接种系统进行测试，对官方方法进行了修改。每个实验室以随机顺序对8个样品进行单次测定。样品包括两种不同市场浓度的牛饲料和猪饲料的重复样本。所有实验室的平均回收率为理论值的110.7%，12个实验室的平均回收率范围为69.4% - 128.6%。一个实验室的结果以及来自不同实验室的另外两个值被视为异常值并被排除在统计分析之外。统计分析得出单次测定的置信区间为±26%。
