gas is nitrogen or helium with a linear velocity of about 35 cm per second, and a split ratio of 1:5. [Note—The split ratio can be modified in order to optimize sensitivity. ] The column temperature is maintained at 40 for 20 minutes, then raised at a rate of 10 per minute to 240, and maintained at 240 for 20 minutes. The injection port and detector temperatures are maintained at 140 and 250, respectively. Chromatograph the Class 1 Standard Solution, the Class 1 System Suitability Solution, and the Class 2 Mixture A Standard Solution, and record the peak responses as directed for Procedure: the signal-to-noise ratio of 1,1,1-trichloroethane in the Class 1 Standard Solution is not less than 5; the signal-to-noise ratio of each peak in the Class 1 System Suitability Solution is not less than 3; and the resolution, R, between acetonitrile and methylene chloride in the Class 2 Mixture A Standard Solution is not less than 1.0.
色谱系统（参见色谱法<621>）――【注意－若操作A得到的色谱结果低于操作B得到的色谱结果，操作B的色谱系统可以被替代】气相色谱由氢火焰离子检测器，0.32mm×30m，装填有厚度为1.8μm厚的G43固定相的熔融石英柱组成。石英柱也可由装填有3.0μm厚的G43固定相，0.53mm×30m大内径开管柱。载气为线速35cm/秒，分流比为1：5的氮气或者氦气。分流比可根据条件修改调整。柱温在40℃维持20分钟，然后以10℃/分钟的速率升至240℃，然后在240℃维持20分钟。进样口和检测器温度分别维持在140℃和250℃。记录一级标准溶液，一级系统适应性溶液 和二级混匀液A标准溶液的色谱，按下列操作记录峰响应值：1，1，1－三氯乙烷在一级标准溶液中的信噪比不得小于5；一级系统适应性溶液 的每个峰的信噪比不得小于3；在二级混匀液A标准溶液中，乙腈和二氯甲
烷的分离度R不得小于1.0。
Procedure— [Note—It is recommended to increase the temperature of the transfer line between runs to eliminate any potential condensation of solvents. ] Separately inject (following one of the headspace operating parameters described in Table 5) equal volumes of headspace (about 1.0 mL) of the Standard Solution, the Test Solution, and the Spiked Test Solution into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the amount, in ppm, of each residual solvent found in the article under test by the formula: 5(C/W)[rU /(rST-rU)]
操作过程――【注-建议增加传输线路间的温度，以消除任何潜在冷凝溶剂】根据表5的一项设定顶空操作参数，将相同体积的（约1.0mL）标准溶液，待测液 和示踪溶液顶空进样，记录色谱并测量主峰的响应值。根据下面的公式计算被检测药品中每个残留溶剂的量，单位为ppm：
5（C/W）[ru/（rst-ru）]
in which C is the concentration, in μg per mL, of the appropriate USP Reference Standard in the Standard Stock Solution; W is the weight, in g, of the article under test taken to prepare the Test Stock Solution; and rU and rST are the peak responses of each residual solvent obtained from the Test Solution and the Spiked Test Solution, respectively.
C为USP标准品在标准溶液中的浓度（μg/ml）；W为用于配制待测储备液 的样品的重量（g）；ru 和rst分别为待测液 和示踪溶液 中每一个残留溶剂的峰值响应。
水不溶物water-insoluble articles
Procedure A— [Note—Dimethyl sulfoxide may be substituted as an alternative solvent to dimethylformamide. ] 操作A (注：二甲基甲酰胺可替代二甲亚砜)
Class 1 Standard Stock Solution— Transfer 1.0 mL of USP Class 1 Residual Solvents Mixture RS to a 100-mL volumetric flask previously filled with about 80 mL of dimethylformamide, dilute with dimethylformamide to volume, and mix. Transfer 1.0 mL of this solution to a 100-mL volumetric flask, previously filled with about 80 mL of dimethylformamide, dilute with dimethylformamide to volume, and mix (reserve a portion of this solution for the Class 1 System Suitability Solution). Transfer 1.0 mL of this solution to a 10-mL volumetric flask, dilute with dimethylformamide to volume, and mix.
一级标准储备液：吸1.0mlUSP一级残留溶剂混匀对照，于事先已加入80ml二甲基甲酰胺的100ml量瓶中，用二甲基甲酰胺稀至刻度，混匀，吸上述溶液1.0ml，于预先加入80ml的二甲基甲酰胺的100ml量瓶中，用二甲基甲酰胺稀至刻度，混匀(作为一级系统适用性溶液)。再吸取1.0ml上述溶液于10ml量瓶中，用二甲基甲酰胺稀至刻度，混匀。
Class 1 Standard Solution— Transfer 1.0 mL of Class 1 Standard Stock Solution to an appropriate headspace vial, containing 5.0 mL of water, apply the stopper, cap, and mix.
一级标准溶液：吸取1.0ml一级标准储备液至已加入5.0ml水的顶
空瓶中，加塞，轧盖，混匀。
Class 2 Standard Stock Solutions— Transfer 1.0 mL of USP Residual Solvents Class 2—Mixture A RS to a 100-mL volumetric flask, previously filled with about 80 mL of dimethylformamide, dilute with dimethylformamide to volume, and mix. This is Class 2 Standard Stock Solution A. Transfer 0.5 mL of USP Residual Solvents Class 2—Mixture B RS to a 10-mL volumetric flask, dilute with dimethylformamide to volume, and mix. This is Class 2 Standard Stock Solution B.
二级标准储备液：吸取1.0ml二级混匀物A对照，至预先加入80ml二甲基甲酰胺的100ml量瓶中，用二甲基甲酰胺稀至刻度，混匀，作为二级混匀A标准储备液。吸取0.5ml二级USP混匀B对照，至10 ml量瓶中，用二甲基甲酰胺稀至刻度，混匀，作为二级混匀物B标准储备液。
Class 2 Mixture A Standard Solution— Transfer 1.0 mL of Class 2 Standard Stock Solution A to an appropriate headspace vial containing 5.0 mL of water, apply the stopper, cap, and mix.
二级混匀A标准溶液：吸取二级混匀A标准储备液1.0ml至顶空瓶中，加水5.0ml，加塞，轧盖，混匀。
Class 2 Mixture B Standard Solution— Transfer 1.0 mL of Class 2 Standard Stock Solution B to an appropriate headspace vial containing 5.0 mL of water, apply the stopper, cap, and mix.
二级混匀B标准溶液：吸取二级混匀B标准储备液1.0ml至顶空瓶中，加水5.0ml，加塞，轧盖，混匀。
Test Stock Solution— Transfer about 500 mg of the article under test, accurately weighed, to a 10-mL volumetric flask, dissolve in and dilute with dimethylformamide to volume, and mix.
测试储备液：准确称取专论下规定约500mg的样品于10ml量瓶中，用二甲基甲酰胺溶解并稀至刻度，混匀。
Test Solution— Transfer 1.0 mL of Test Stock Solution to an appropriate headspace vial, containing 5.0 mL of water, apply the stopper, cap, and mix.
测试溶液：吸取1.0ml测试储备液至顶空瓶中，加水5.0ml，加塞，轧盖，混匀。
Class 1 System Suitability Solution— Mix 5 mL of Test Stock Solution with 0.5 mL of the intermediate dilution reserved from Class 1 Standard Stock Solution. Transfer 1.0 mL of this solution to an appropriate headspace vial, containing 5.0 mL of water, apply the stopper, cap, and mix.
一级系统适用性溶液：吸取5ml测试储备液与0.5ml一级标准储备溶液的中间稀释浓度溶液。吸取上述溶液1.0ml至顶空瓶中，加5.0ml水，加塞，轧盖并混匀。
Chromatographic System (see Chromatography 621— The gas chromatograph is equipped with a flame-ionization detector and a 0.53-mm × 30-m wide-bore column coated with a 3.0-μm layer of phase G43. The carrier gas is helium with a linear velocity of about 35 cm per