happyjyl
第2楼2007/06/27
你的理解好像是必要时加入聚乙二醇和二苯醚后一起加热,而我的理解是必要时加入聚乙醇后用预先加热的二苯醚溶解。这只是从字面上理解的意思,我对实验不太懂,具体的还得问茅茅姐。
深海的海豚
第5楼2007/06/27
我觉得应该是“取50.0g聚二乙醇于75ml提前预热的二苯醚使溶解, 必要时,于250ml蒸馏瓶中加热使聚乙二醇熔化。”
ps:二苯醚熔点:28℃。
何当奇
第6楼2007/06/28
前面大家所说也是我的意见
Within 2-5 minutes, concomitantly determine the absorbances of the solutions in 1-cm cells at the wavelength of maximum absorbance at about 450nm, with a suitable spectrophotometer, using a blank consisting of a mixture of 15.0ml of ceric ammonium nitrate solution and 10.0ml of a mixture of equal valumes of freshly distilled acetonitrile and water :the absorbance of the solution from the Test preparation does not exceed that of the solution from the standard preparation, corresponding to not more than 0.25% of combined ethylene glycol and diethylene glycol.
这句要商讨一下.
不过还真是不习惯USP这个英语的表示方法