Problematic separation

[Jackus]

Thank you Vlad, interesting columns. I never heard about it .
So I have a lot to test now. Thank you guys.

Regards

[ym3142]

The analyte’s oxygen draws the electron cloud towards it self thus creating a permanent dipole moment (partly negative). This is how hydrogen bonding works. So negatively charged oxygen (i.e. ionized silanol) will repel this particular molecule even in its neutral state.

sorry out of topic but very interesting idea.
Danko, do you have actual result which shows an non-ionnizable molecule varys it retention a lot due to different pH. Please make sure there are no COOH, no N(can be in amide), no phenolic OH, no -SOnH, or other ionic groups

[danko]

Hi ym3142,

Unfortunately I haven’t got real life data, demonstrating my point – just a theoretical reflection.
But I was hoping that Sadilek would perform the test, since he has the “rightâ€

[Jackus]

Yes, you may be sure that I'll give you some clue. But I have available instrument on Monday. You must withstand

[ym3142]

Danko,

Thank you.

I will keep your idea in mind so I can use it to explain some case in the future.

[banala_b]

Hi all,
I am working on Insulin molecule,which is combined with gelation.
My diluent is 0.01N Hcl,when im adding diluent,gelatin present along with sample is creating a thick gel in flask,and at room temperature its solidifying.I am injecting thick viscous liquid(as its hard to filter)
I am getting poor recovery of insulin,Can anyone suggest how to get rid of gelatin interference from sample(any special filters available,),centrifuge of sample did not work.
Or would using a diluent which could dissolve gelatin would work?
I will thankful for all suggestions

[ym3142]

Banala,

why did you start a new topic for yourself?

Gelatin is soluble in most polar solvent so try to dissolve it by adding solvent

[Bryan Evans]

banala_b -

Protein precipitation is an option - but recovery can still be an issue.
Heat could help the gelatin from coagulating.
Maybe someone else in the forum has experience with this and can
provide you with an extraction technique.

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A second option is to try dissolving the gelatin in these 2 solutions:
A. 0.1% TFA (gelatin might coagulate just like it does in HCl)
B. 50-100mM NH4AcOH (neutral)

If it dissolves readily in either of those solutions - we might be able to help. Below are applications of insulin
and large proteins injected on to Intrada WP-RP and Cadenza HS-C18:

http://www.silvertonesciences.com/files/TI289E.pdf
http://www.silvertonesciences.com/files/TI290E.pdf

We don't have any data on gelatin - so no clue if it will work. The
mwt of the gelatin is also a factor.

[Tomasz]

It looks like there are two topics in one place.

Sadilek!
You can try a Hypercarb column. It is a very retentive column containing 100% carbon. You will have no problem with short retention times. Nevertheless, it is not a cheap column

[yangz00g]

My impression with the discussion here is that few folks here in LC field have solid organic background or too solid to care. As Virtu pointed out, the molecue structure provided here is bizzard at first glimps the C--OO group). You need to get right structure of the molecule first.

[Bruce Hamilton]

As noted earlier in the thread, most employers would be very concerned if correct chemical structures were posted here without full prior approval. Dismissal would be a possible consequence.

Posters should be very careful about not disclosing confidential infiormation to any people who have not signed a NDA with their employer.

I just assume people will post or describe the salient molecular functional groups and structural components of an analyte, or even a surrogate. This isn't the Totally Synthetic blog.

Bruce Hamilton

[Tomasz]

yangz00g

It looks like the structure is wrong because of problem connected with a program used to draw it. I had similar problems with one such program several month ago. You must use different option to get right structure in this program. Please just imagin that COO is a deprotonated carboxylic group and the bond should be connected with O atom instead of C atom.

Regards
Tomasz

[HW Mueller]

Danko, on this ion-dipole interaction, etc.: You know that an ion-ion interaction is stronger, but even that can be washed out if enough ions are in the mobile phase. My guess is that such ion-dipole interactions, etc., are completely "washed out" by H2O and polar organics in the mobile phase. As a consequence, I think, I have never seen pH effects on non-ionizeable molecules.

[danko]

Hi Hans,

While I recognize the validity of your point, I would like to redirect your attention to my point:
The ion-dipole interaction was the one I regarded as undesirable, because these two (the negative ion and the negative part of the dipole) would try to avoid each other and thus counteract the retention, which might or might not be influenced noticeably by that interaction.
The interaction I tried to promote as a means of retention facilitator was the hydrogen bonding which is perfectly compelling to take into account, due to its strength. So, you should really see it the other way around.
Having said that, I will, once again, emphasize that I was just speculating - i.e. no data to show.
So let’s see what the test shows. As I always say: An experiment is worth thousand hypotheses

Best Regards

[Jackus]

Hold on, analysis is in progress. I'll past chromatograms here.