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何当奇
第21楼2008/10/21
METHOD III (GRAVIMETRIC)
Procedure for Chemicals— Proceed as directed in the individual monograph preparing the chemical as directed under Loss on Drying 731 .
Procedure for Biologics— Proceed as directed in the individual monograph.
Procedure for Articles of Botanical Origin— Place about 10 g of the drug, prepared as directed (see Methods of Analysis under Articles of Botanical Origin 561 ) and accurately weighed, in a tared evaporating dish. Dry at 105 for 5 hours, and weigh. Continue the drying and weighing at 1-hour intervals until the difference between two successive weighings corresponds to not more than 0.25%.
方法III（重量分析法）
化学药品的操作---参照各论所示进行操作，准备化学药品如干燥失重所示。
生物药品的操作---参照各论所示进行操作。
植物起源的药品的操作---参照（植物起源的药品<561>的分析方法）所示，准备10g药品，准确称量，置一个去皮重的蒸发皿中。于105℃干燥5小时，称重。继续干燥，间隔1小时后称重，直到连续两次称重的差别不超过0.25%。
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影子
第30楼2009/02/20
请教有过操作经验的各位：
一原料药，水分含量应不超过1%，按USP规定应该用酒石酸钠作为水标准物质标定F值，但当我按上述操作程序标定时，却发现消耗的卡尔试剂非常少，因此计算出来的F值过大（超过20），这显然是失真的；我直接用水作标准物质标定出的F值一般在3点几。标定时所用溶剂均为甲醇，请大家帮我分析下这是什么原因？redanqi 发表:Standardization of the Reagent— Place enough methanol or other suitable solvent in the titration vessel to cover the electrodes, and add sufficient Reagent to give the characteristic endpoint color, or 100 ± 50 microamperes of direct current at about 200 mV of applied potential.
卡尔溶剂的标定---将足量体积的甲醇或其他合适溶剂至滴定容器中，覆没电极，加入足量的卡尔试剂至给出特征性的终点颜色，或者在大约200mV的应用电势下达到100+-50微毫安的直流电。
For determination of trace amounts of water (less than 1%), it is preferable to use Reagent with a water equivalency factor of not more than 2.0. Sodium tartrate may be used as a convenient water reference substance. Quickly add 75 to 125 mg of sodium tartrate (C4H4Na2O6•2H2O), accurately weighed by difference, and titrate to the endpoint. The water equivalence factor F, in mg of water per mL of reagent, is given by the formula:
2(18.02/230.08)(W/V)
in which 18.02 and 230.08 are the molecular weights of water and sodium tartrate dihydrate, respectively; W is the weight, in mg, of sodium tartrate dihydrate; and V is the volume, in mL, of the Reagent consumed in the second titration.
为了测定痕量水分（少于1%），最好使用与水的等价因子不超过2.0卡尔试剂。酒石酸钠可以用于作为一种方便的水标准物质。快速加入75~125mg的酒石酸钠，减重法准确称量，滴定至终点。水的等价因子F，以每毫升卡尔试剂消耗水的质量mg计，用以下公式计算：2(18.02/230.08)(W/V)
其中18.02和230.08是水和酒石酸钠的各自分子量，W是二水酒石酸钠的重量，以mg计，V是第二次滴定消耗的卡尔试剂的体积，以毫升计。