Katz S E, Fassbender C A
J Assoc Off Anal Chem. 1978 Jul;61(4):918-22.
The microbiological assay for penicillin residues in milk was improved. Acidification of milk with phosphoric acid to pH 4.5, centrifugation to remove precipitated proteinaceous matter, adjustment of pH to 6.0, a second centrifugation, and the use of a 2% agar base layer resulted in the consistent measurement of 0.01 unit penicillin activity/ml milk. Sarcina lutea was used as the assay organism. Recoveries in milk averaged 94%, in nonfat dry milk 84%, in cottage cheese 97%, and in cream cheese 94%.
牛奶中青霉素残留的微生物检测方法得到了改进。用磷酸将牛奶酸化至pH 4.5，离心去除沉淀的蛋白质物质，将pH调至6.0，再次离心，并使用2%的琼脂基层，可实现对牛奶中每毫升0.01单位青霉素活性的一致测量。藤黄八叠球菌用作检测微生物。牛奶中的回收率平均为94%，脱脂奶粉中为84%，农家干酪中为97%，奶油干酪中为94%。
