Help with Pramipexole dichloride monohydrate

[Tequila]

Dear members of this forum,

I need your help in order to get good results in my HPLC analysis. I have problems with Pramipexole dichloride monohydrate. I am working with a mobile phase consisting of: TFA 0.1% - Acetonitrile (95:5) with C18 column and I do not like a lot because I work with a new column and the peak has a very important tailing (it reach to the base line in two minutes) and the asimetry is worst with the increasing of the inyections.
In my opinion the mobile phase is very agressive to the column and the tecnique was provided by the manufacturer of the drug. I would apreciate any help by any way; experience or information in differente web sites with application notes.
Thanks in advance for your help,

Diego

[Mark Tracy]

The mobile phase is aggressive, but some columns withstand it better than others. You may want to shop around for columns. TFA is used because it sharpens peaks for bases better than most other common acids. (It has various other advantages and disadvantages. This subject has been talked to death elsewhere on the Forum.) You can slow down the degradation of the column by storing it in acid-free mobile phase between uses.

Your other options would be ion-pairing, cation-exchange, or mixed RP/WCX. Any of those are potentially good methods, but that would be a bunch of work to develop and validate. A quick Google search turned up several leads.

[Bryan Evans]

Our Unison UK C18 column might work well for your
application. It can be used with 100% aqueous mobile phase
(without phase collapse) and is durable under acidic conditions.

Let me know if you are interested.

http://www.silvertonesciences.com/?SCRE ... var=LINK_1


http://www.silvertonesciences.com/?SCRE ... var=LINK_1

[Uwe Neue]

Packings with a multi-functional bonding chemistry are better for TFA applications than packings with a mono-functional surface chemistry. I do nto think that 5% organic is terribly critical, but if you want to play it safe, you may want to choose a surface chemistry that is compatible with highly aqueous mobile phases.

Among the Water products, I would recommend the XBridge C18 or the Atlantis dC18. If you go on our website, you will find for example applications for peptides and an application of vitamins using a TFA gradient.

[yangz00g]

Many C18 coulmns now can handle 100% aqueous mobile phase as stated in the previous replies.

I will think that your problem is column overloading, e.g, injection volume is too large, which is evident by apperance of broader peaks after a few injections. A simple test is either reduce the injection vloume or extend the run time to see if peak gets broader after some injections