Procedure— Ignite a suitable crucible (for example, silica, platinum, quartz, or porcelain) at 600 ± 50 for 30 minutes, cool the crucible in a desiccator (silica gel or other suitable desiccant), and weigh it accurately. Weigh accurately ◆1 to 2 g of the substance, or◆ the amount specified in the individual monograph, in the crucible.
Moisten the sample with a small amount (usually 1 mL) of sulfuric acid, then heat gently at a temperature as low as practicable until the sample is thoroughly charred. Cool; then, ◆unless otherwise directed in the individual monograph, ◆moisten the residue with a small amount (usually 1 mL) of sulfuric acid; heat gently until white fumes are no longer evolved; and ignite at 600 ± 50 , ◆unless another temperature is specified in the individual monograph, ◆ until the carbon iscompletely incinerated. Ensure that flames are not produced at any time during the procedure. Cool the crucible in a desiccator (silica gel or other suitable desiccant), weigh accurately, and calculate the percentage of residue.
用少量（通常1mL）硫酸润湿该样品，然后在尽可能低的温度下温和加热至该样品彻底炭化。放凉；然后，◆除非在具体的各论中另有规定◆，以少量（通常1mL）硫酸润湿残渣；温和加热直到白色浓烟不再析出；再于600 ± 50 条件下，◆除非各论中规定其他的温度◆，灼烧，至碳被彻底焚化。确保在此步骤中的任何时间均不得出现火焰。在干燥器（硅胶或其他适当的干燥剂）中放凉该坩锅，精确称重，并计算残渣的百分比。