From the information available for the preparation to be assayed (the “Unknown”), assign to it an assumed potency per unit weight or volume, and on this assumption prepare on the day of the assay a stock solution and test dilution as specified for each antibiotic but with the same final diluent as used for the USP Reference Standard. 从供试品可知的信息（未知物），确定一个设想的效价/单位重量或体积，根据这个假设在分析当天制备储备液并对各抗生素按指定的方法稀释但是最终稀释剂应与其USP标准品所用一致。