Hi all,
Why do most of the carboxylic acids with chloro groups attached ,tail?(even at ion pair condition?)Is there really a remedy or to be lived with/

What is your pH, your column? I have never seen such things tail

You can achieve good peak symmetry via anion exchange for these compounds. For example, Dionex sells a column (the IonPac AS16) which gives very good peak symmetry for chloro acids as well as bromo acids.

Thanx cris, for the suggestion
and sorry anon sept'05- for my hasty generalisation.My compound is
Cl-CH2-C(=O)-C(=N-OCH3)-COOH,any body has idea what makes the compo' to tail?

also you can look at the Metrohm Met Supp 5 anion exchange column as an alternative to Dionex.
Look at the following links for example appliations from Metrohm. http://www.metrohm.com/docs/app/notes/pdf/s121.pdf
and
http://www.metrohm.com/docs/app/notes/pdf/s94.pdf

S-94 Determination of chloroacetates in long-chain carboxylic acids

S-121 Determination of fluoride, glycolate, monochloroacetate and chloride in a sufactant solution

What do you know about the ability of this compound to form metal complexes?

formation/equilbration of the C=O adjacent to the C=N-OCH3 to a cyclic ring structure formation(s) ?

just a guess.

As I said, I wouldn't be surprised if this compound is chelating with metals. If this is the problem, add a chelator to your mobile phase that works under the conditions that you use. People use commenly EDTA, but you should check if it actually is functional in your mobile phase.

Dear anon [sept'9th,2:53],
Do you mean to say the problem will be sorted if a polymeric c18 is used?, (where metal interaction is expected to be nil or less)
.....Over to all

Extending Anon Sept. 9, 7:45am: It wouldn´t be surprising if your compound were unstable. What happens if you reinject a collected "peak"?

To Anon Sept. 8, 4AM,

Vendors should identify themselves when making posts in this forum. It is not appropriate for vendors to post anonymously.

I did not say that a polymeric column would solve the problem. I suggested to use EDTA in your mobile phase. This is the common fix. In addition, I am not sure that a polymeric column would fix the problem, since the metals are coming from the frits and the instruments. You could solve the problem by using a metal-free system with a metal free-column, but I guess this might be a little bit more expensive than a small bottle of EDTA. Of course, if you prefer the instrument, be my guest...

Dear anon September 10, 2003 - 04:43 pm,
I have a similar problem,can you suggest the quantity range of EDTA ,which could be used comfortably in to the system? And can it be operated at all pH?
thanks in advnce

Dear anon Sept 10, 04:43 pm,
I have a similar problem,can you suggest the quantity range of EDTA ,which could be used comfortably in to the system? And can it be operated at all pH?
thanks in advance

Sorry, haven't been here in several days.
5 mM EDTA is plenty. After the inital wash, you can probably reduce it to 1 mM for maintainance.

Thanks for all the suggestions
-Originator

To Chris Pohl, Dionex

I totally agree with your request that vendors should identify themselves.
Also Metrohm people have been instructed to do so.
In the case of Anon Sept. 8, 4pm I assume that this was a happy customer as the column name is not spelled correctly.

Markus,

Perhaps you are right but I suspect otherwise. The text in question doesn't sound very much like a customer testimonial. It sounds more like anonymous vendor comments. Why would a customer include a comment like "also you can look at the Metrohm Met Supp 5 anion exchange column as an alternative to Dionex" in the introduction to the post. A happy customer would have started out with some comment regarding why they were particularly impressed with the Supp 5 rather than starting out with a commercial comment as in the case of the posting in question. Furthermore, while happy customers occasionally include Web links, they rarely include inappropriate Web links as in the posting in question.