主题：【求助】关于美国药典注射剂各论中 含量测定供试品溶液的配制问题

美国药典注射液各论配制供试品溶液常看到
Assay preparation 1 (where it is represented as being in a single-dose container)
Assay preparation 2 (where the label states the quantity of ampicillin in a given volume of constituted solution)

例如注射用氨苄西林
Assay preparation 1 (where it is represented as being in a single-dose container)—Constitute Ampicillin for Injection in an accurately measured volume of Diluent, corresponding to the volume of solvent specified in the labeling. Withdraw all of the withdrawable contents, using a suitable hypodermic needle and syringe, and quantitatively dilute with Diluent to obtain a solution containing about 1 mg of ampicillin per mL. Use this solution promptly after preparation.

Assay preparation 2 (where the label states the quantity of ampicillin in a given volume of constituted solution)—Constitute 1 container of Ampicillin for Injection in a volume of Diluent, accurately measured, corresponding to the volume of solvent specified in the labeling. Quantitatively dilute an accurately measured portion of the constituted solution with Diluent to obtain a solution having a concentration of about 1 mg of ampicillin per mL. Use this solution promptly after preparation.

我翻译的是
供试品溶液1（当以一次性剂量容器标示时）
供试品溶液2（当以临用前溶液所含氨苄西林的量标示时）

不过始终不清楚到底这两种剂型到底是怎么回事。实际的制剂到底是什么样情况什么时候用1，什么时候用2？
希望有人给予解答！