作者ecound (对时间没感觉)
看板Chemistry
标题[分析]一题研所题目
时间Tue Mar 3 22:21:43 2009
麻烦了 想了很久 也翻过课本 还是没什麽头绪
The reverse-phase analysis of a mixture of these fatty acids , CH3CH2CH2COOH
, CH3COOH ,gave two peaks but very poor separation of the peaks when using a
10% methanol-buffered water (pH = 6) mobile phase . To achieve essentially
baseline resolution , when modification in procedure would be needed ?
please explain why you did the modification. pKa are 4.74 and 4.82 for
CH3COOH and CH3CH2CH2COOH , respectively .
感谢
--
※ 发信站: 批踢踢实业坊(ptt.cc)
◆ From: 218.170.137.127
1F：→ little1516:逆.动.极 与acid特有强氢键二聚体有关？ 03/03 23:14
2F：→ little1516:也许 仪分翻一翻 有机-酸的特性那翻一翻 就想出答案喽 03/03 23:14
3F：推 buteo:把pH值调到4.8 让两者的R-COOH与R-COO-比相差加大 03/04 00:53
4F：推 buteo:因为在pH=6时 物种几乎都是以RCOO-方式存在 03/04 00:54
5F：→ buteo:这是我的猜想 感觉会特别提pKa是别有用意 03/04 00:54
6F：推 innevertears:pKa在4.82左右 CH3COOH以离子方式存在的比另一个多 03/04 01:00
7F：→ innevertears:改用ICE? 03/04 01:00