主题：【讨论】USP-limit of EG and DEG translation

请教我的理解是否正确.差不多的话,就按这样的步骤做实验了哦.谢谢

Ceric ammonium nitrate solution---dissolve 6.25g of ceric ammonium nitrate in 100ml of 0.25N nitric acid. Use with 3 days.

硝酸铈铵溶液---把6.25g 硝酸铈铵溶于100ml 0.25N 硝酸, 有效期三天

Standard preparation---transfer 62.5mg of diethylene glycol to a 25ml volumetric flask, dissolve in a mixture of equal volumes of freshly distilled acetonitrile and water, dilute with the same mixture to volume, and mix

标准溶液配制----移取62.5mg 二甘醇 于25ml 容量瓶, 用乙腈水溶液(体积比为1: 1)溶解, 并定容至刻度, 摇匀.

Test preparation---dissolve 50.0g of polyethylene glycol in 75ml of diphenyl ether, previously warmed, if necessary, just to melt the crystals, in a 250ml distilling flask. Slowly distill at a pressure of 1mm to 2mm of mercury, into a receiver graduated to 100ml in 1 ml subdivisions, until 25ml of distillate has been collected. Add 20ml of water to the distillate, shake vigorously, and allow the layers to separated. Cool in an ice bath to solidify the diphenyl ether and facilitate its removal. Filter the separated aqueous layer, wash the diphenyl ether with 5.0ml of ice-cold water, pass the washings through the filter, and collect the filtrate and washings in a 25-ml volumetric flask. Warm to room temperature, dilute with water to volume, if necessary, and mix. Mix this solution with 25.0ml of freshly distilled acetomitrile in a glass-stoppered, 125-ml conical flask.

测试溶液配制---于250ml蒸馏瓶中家50.0g聚乙醇和75ml二苯醚, 有需要的话, 加热使聚乙醇熔化, 减压蒸馏(1-2毫米汞柱), 收集于100ml 带刻度的接收瓶(分度值1ml)中, 当收集到25ml后停止蒸馏. 加20ml水到馏分中, 摇匀, 让其分层. 然后放入冰浴中冷却至二苯醚凝固. 过滤已分离的水层, 用5.ml的冰水洗涤二苯醚, 合并滤液和洗涤液. 将其移如25ml容量瓶中, 放置至室温, 用蒸馏水定容至刻度. 将此溶液和25ml新蒸的乙腈倒入带塞的125ml锥形瓶中.

Procedure---transfer 10.0ml each of the standard preparation and the test preparation to separate 50-ml flasks, each containing 15.0ml of ceric ammonium nitrate solution, and mix. 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

程序---分别移取10.0ml标准溶液和测试溶液于加有15.0ml硝酸铵铈的50ml烧杯, 混合均匀. 在2-5分钟内, 在450nm处测其最大吸光度. 空白溶液为15ml硝酸铵铈溶液和10.0ml的乙腈水溶液(体积比为1: 1). 测试溶液的吸光度不得超过标准溶液的吸光度, 这就等于聚乙醇中乙二醇和二甘醇总和含量不超过的0.25%