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[交流]
【求助】求助:水分測定!!
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USP標準中,水分測定項:The test preparation being prepared as directed for a hygroscopic specimen. 怎么理解這句話? 謝謝! |
木蟲 (著名寫手)
木蟲之王 (文壇精英)
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請參考usp以下論述 Where the monograph specifies that the specimen under test is hygroscopic, use a dry syringe to inject an appropriate volume of methanol, or other suitable solvent, accurately measured, into a tared container, and shake to dissolve the specimen. Using the same syringe, remove the solution from the container and transfer it to a titration vessel prepared as directed for Procedure. Repeat the procedure with a second portion of methanol, or other suitable solvent, accurately measured, add this washing to the titration vessel, and immediately titrate. Determine the water content, in mg, of a portion of solvent of the same total volume as that used to dissolve the specimen and to wash the container and syringe, as directed for Standardization of Water Solution for Residual Titrations, and subtract this value from the water content, in mg, obtained in the titration of the specimen under test. Dry the container and its closure at 100 for 3 hours, allow to cool in a desiccator, and weigh. Determine the weight of specimen tested from the difference in weight from the initial weight 4of the container. 當各論指明樣品在測試條件下具有引濕性時,使用一個干燥的注射器注入合適體積的甲醇或其他合適的溶劑,準確測量,至一個去了皮重的容器中,振搖使樣品溶解。使用同一注射器,從容器中移取溶液轉(zhuǎn)移至按規(guī)程準備的滴定容器中。用第二部分的甲醇或其他合適的溶劑重復上述操作,準確測量,將這一部分洗滌物加至滴定容器中,立即滴定。如回滴定法水試劑的標定所示,測定與溶解樣品和清洗容器與注射器相同體積的的溶劑的水的含量,以mg計,然后從待測樣品滴定獲得的水的含量中扣除掉這部分值,以mg計。在100℃,干燥容器和它的塞子3小時,干燥器中放冷,稱重。與容器初始的重量的差值就是測試樣品的重量。 |
銀蟲 (初入文壇)

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