d****n
发帖数: 237 | 1 我最近制备了几组基于甲基丙烯酸二甲氨基乙酯的季铵盐类聚合物，然后分别在北
京化工大学、复旦大学和中科院化学所进行水相GPC测试其分子量，GPC包括Waters、PL
和Agilent，流动相包括纯水和0.1MNaNO3水溶液，检测器包括RI、RI+MALLS等，但是都
遇到了共同的问题，我配备的质量浓度大约30mg/10ml，但是大多数样品都无法检测其
浓度信号，因而无法得到分子量。
我现在想的一个问题是，是不是我的样品溶解于水中后，由于溶液的折光指数与纯
流动相的折光指数几乎一样，因此RI检测器检测不到其信号，因此必须选择其它的浓度
检测器。我的问题是，据你们所知，哪些聚合物不适合用RI检测器？
多谢。 |
a*i
发帖数: 1652 | 2 the refractive index of solution and mobile phoase should be quite different.
other issues to consider:
1) is the injection volume too small?
2) is the molecular weight too small (oligmer)?
3) what's the type of column? |
h*********g
发帖数: 78 | 3 i had the same problem like you, in may case it is a block copolymer. my
guess is the interaction between the polyelectrolyte and column, so try to
use other method to calculate the moleculer weight instead of GPC. |
p******4
发帖数: 38 | 4 what you said is right. 3mg/ml concentration is somewhat low. maybe you want
to try higher. RI is a most used detector. you can also try UV detectors. |
i***y
发帖数: 190 | 5 3mg/ml concentration is high enough...one possibility is that your polymer or
copolymer is a highly aggregated polymer, which means there is no indivadual
marcomolecules in the polymer solution, just big particles. If the
particles are big enough, say >0.45micron, after filtering, no polymers will
be left in the solution, or cut off by guard columns. If so, no signal can
be detected in main columns. The viscosity measurement will tell you how
serious your polymer aggregation is.
PL
【在 d****n 的大作中提到】
: 我最近制备了几组基于甲基丙烯酸二甲氨基乙酯的季铵盐类聚合物，然后分别在北
: 京化工大学、复旦大学和中科院化学所进行水相GPC测试其分子量，GPC包括Waters、PL
: 和Agilent，流动相包括纯水和0.1MNaNO3水溶液，检测器包括RI、RI+MALLS等，但是都
: 遇到了共同的问题，我配备的质量浓度大约30mg/10ml，但是大多数样品都无法检测其
: 浓度信号，因而无法得到分子量。
: 我现在想的一个问题是，是不是我的样品溶解于水中后，由于溶液的折光指数与纯
: 流动相的折光指数几乎一样，因此RI检测器检测不到其信号，因此必须选择其它的浓度
: 检测器。我的问题是，据你们所知，哪些聚合物不适合用RI检测器？
: 多谢。
|
p******4
发帖数: 38 | 6 If the particle size is over 0.45 micron, then it is not in a solution.
Ivsky, would you please explain more about the viscosity measurement, such
as the method, instrument or any details? You are not mentioning the
viscosity detector in GPC, right?
Thanks, |
