[中文]含量分析——
流动相——将5.75克磷酸二氢铵溶解于700毫升水中，加入3.2毫升40%的四丁基氢氧化铵溶液，280毫升甲醇及25毫升四氢呋喃，混匀。用磷酸调节pH至4.5± 0.1，采用0.5微米过滤器或微孔过滤并脱气。必要时可做些调整（见色谱法 621下的系统适配性）

标准溶液——将准确称取的USP RS级头孢美唑溶解于流动相中，得到的溶液中每毫升需含有200微克头孢美唑(C15H17N7O5S3)。【注意：该溶液配制好后在10分钟内使用】

分离度测试溶液——将USP RS级头孢美唑溶解于0.00N氢氧化钠溶液中，制备得1mg/ml头孢美唑溶液。95℃加热10分钟。每毫升该溶液中加入2毫升标准溶液，并用流动相稀释至20ml。该溶液含有头孢美唑和头孢美唑内酯（溶解物）。

待测试剂——将准确称取的20mg头孢美唑原料移入100ml容量瓶中，用流动相稀释至刻度，混匀。【注意：配好后该溶液在10分钟内使用】

色谱系统（见色谱法 621）—— 液相色谱仪需安装214纳米检测器和一个容量为4.6毫米×25厘米的填充L1填料的色谱柱。流速为2毫升每分钟。分辨率分析溶液进行色谱分析，按照分析步骤中要求的方法记录峰值：头孢美唑和头孢美唑内酯的分辨率R不低于3.0。标准溶液进行色谱分析，按照分析步骤中要求的方法记录峰值：柱效率不少于1250理论塔板；拖尾因子大于0.94小于1.6；重复进样的相对标准偏差低于2.0%。

步骤——分别取等量的（大约10微升）标准溶液和待测溶液注入色谱仪，记录色谱图并测量主峰面积。按照以下公式计算每毫克头孢美唑原料中头孢美唑的含量，单位为微克：
100(C / M) (rU / rS)
C代表标准溶液中头孢美唑的浓度，单位为微克每毫升；M代表待测试剂中头孢美唑原料的质量，单位为毫克；rU和rS分别代表待测溶液和标准溶液的头孢美唑的峰值。
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[外文]Assay—
Mobile phase— Dissolve 5.75 g of monobasic ammonium phosphate in 700 mL of water, add 3.2 mL of a 40% solution of tetrabutylammonium hydroxide, 280 mL of methanol, and 25 mL of tetrahydrofuran, and mix. Adjust with phosphoric acid to a pH of 4.5 ± 0.1, pass through a filter having a 0.5-µm or finer porosity, and degas. Make adjustments if necessary (see System Suitability under Chromatography 621 ).

Standard preparation— Quantitatively dissolve an accurately weighed quantity of USP Cefmetazole RS in Mobile phase to obtain a solution having a known concentration of about 200 µg of cefmetazole (C15H17N7O5S3) per mL. [note—Use this solution within 10 minutes.]

Resolution solution— Prepare a solution of USP Cefmetazole RS in 0.00 N sodium hydroxide containing about 1 mg per mL. Heat at 95 for 10 minutes. To 1 mL of this solution add 2 mL of Standard preparation, and dilute with Mobile phase to obtain 20 mL of solution. This solution contains cefmetazole and cefmetazole lactone (resolution compound).

Assay preparation— Transfer about 20 mg of Cefmetazole, accurately weighed, to a 100-mL volumetric flask, dilute with Mobile phase to volume, and mix. [note—Use this solution within 10 minutes.]

Chromatographic system (see Chromatography 621 )—The liquid chromatograph is equipped with a 214-nm detector and a 4.6-mm × 25-cm column that contains packing L1. The flow rate is about 2 mL per minute. Chromatograph the Resolution solution, and record the peak responses as directed for Procedure: the resolution, R, between cefmetazole and cefmetazole lactone is not less than 3.0. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the column efficiency is not less than 1250 theoretical plates; the tailing factor is not less than 0.94 and not more than 1.6; and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the areas for the major peaks. Calculate the quantity, in µg, of cefmetazole (C15H17N7O5S3) in each mg of Cefmetazole taken by the formula:
100(C / M)(rU / rS)
in which C is the concentration, in µg per mL, of cefmetazole (C15H17N7O5S3) in the Standard preparation; M is the quantity, in mg, of Cefmetazole taken to prepare the Assay preparation; and rU and rS are the cefmetazole peak responses obtained from the Assay preparation and the Standard preparation, respectively.
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