Any experience of the BioTrap column?

[Mattias]

Hi,

I wonder if any of you have experience in using the BioTrap precolumn, for extraction of pharmaceuticals in complex samples?

In theory it sounds very promising, since it is sort of a mix of SEC and RP.

What I am worried about is the recovery of the active, since the RP activity is only inside the particle (no C18 chains on the outside).

[Mark Tracy]

This is an example of "Restricted Access Media" and the technology has been around since the mid 80s. The exterior of the particles is also coated so you don't have to worry about your active sticking to bare silica. But when dealing with complex biological matrices, there is only one way to find out if it will work: do the experiment.

[Mattias]

Thanks,

Do you know of any other examples of these restricted access media? I know there was a lot of talk about molecular imprinted materials in the mid 90's, but not so much nowadays.

I want to use the material to separate my active from ennoying excipients (such as gelatine and dextrins), before injecting on the analytical column.

[Bryan Evans]

One thing to look at when evaluating these types of columns
is whether or not the vendors have any data under gradient elution.
What you will often find is that it is usually done under isocratic
(approximately 15% organic) conditions using phosphate buffers.

Cadenza HS-C18 is unique in that it can be used under gradient
elution (without protein coagulation) - and good peak shape can
be obtained for basic compounds using NH4AcOH (for LC-MS or prep
work).

If the mwt of your excipients is > 30,000 Da - Cadenza HS-C18
should exclude them:
http://www.imtakt.com/TecInfo/TI290E.pdf

[HW Mueller]

There was a discussion not too long ago in which I pointed out that Imtakt recommends to pretreat samples (0.45 or 0.2 µm filter) before injecting a sample. Also, they point out that using a guard column can be a good idea. My own extensive experience with Pinkerton columns corroborate this. We sometimes got plasma/serum from patients which caused total blockage of the column on one injection, and everything between that and no determinable effect on resistance. We solved problems by adding some Na2SO4 and centrifuging prior to injection.
Columns by Merck, Supelco, and Chrompack indicated that these were rather more prone to problems due to direct injection than even the Pinkerton.

[Bryan Evans]

Cadenza HS-C18 is a unique design, so one should evaluate
whether filtration is necessary for their application.

If the plasma is diluted with internal std., than simply using the
guard column might be sufficient.

[Mattias]

Bryan> Do you know if it is possible to buy this column in Denmark? There doesn't seem to exist a distribution system in Europe.

[Bryan Evans]

Hi Mattias -

Yes, Imtakt has distributors in Europe. If you email them they can
further assist you:

info@imtakt.com