PharmPK Discussion - LC/MS/MS vial adsorption problem

PharmPK Discussion List Archive Index page

On 12 May 1999 at 13:22:14, David_Bourne (david.aaa.pharm.cpb.uokhsc.edu) sent the message


Looking for help in troubleshooting a method development project.
Developing LC/MS/MS method to quantitate pg levels of test article in
plasma.  We are seeing reproducibility problems at the lower
concentrations of the curve and QCs.   We have partially isolated the
problem to adsorption to certain vials (even silinized).  Does anyone
have recommendations for a brand and supplier (catalogue # if available)
for a high quality vial that they have personal experience using that
has no adsorptive qualities at pg levels?

Any other helpful practical hints in regards to method development in
the pg range would also be appreciated.  Thanks.

- Submitted by a member of the list

Back to the Top

On 12 May 1999 at 22:37:05, David_Bourne (david.-at-.pharm.cpb.uokhsc.edu) sent the message

Date: Wed, 12 May 1999 17:15:55 -0400
From: Sriram 
X-Accept-Language: en
MIME-Version: 1.0
To: PharmPK.aaa.pharm.cpb.uokhsc.edu
CC: Multiple recipients of PharmPK - Sent by 
Subject: Re: PharmPK LC/MS/MS vial adsorption problem

If you need non-stick autosampler vials then the info below might help.
We use Unison polypropylene vials from Sun International (1800 522 8425)
CAT No: 200046 for vials- regular price for case of 1000 = $ 123.45
Cat No: 200100 for aluminus seal w/ rubber septum - price for case of 1000 =
$69.70
We havent seen adsorption problems yet. So far we ve only used them for
steroids though.

---

From: Stanley110.-a-.aol.com
Date: Wed, 12 May 1999 21:24:19 EDT
Subject: Re: PharmPK LC/MS/MS vial adsorption problem
To: PharmPK.at.pharm.cpb.uokhsc.edu
MIME-Version: 1.0

In a message dated 5/12/99 3:13:47 PM CST, david.-at-.pharm.cpb.uokhsc.edu writes:

>  We have partially isolated the
>  problem to adsorption to certain vials (even silinized).

David,

What evidence have you that it is absorption to the glass?

Consider adsorptive loss to the stopper as well.

It is well known that silicone rubber selectively adsorbs from a solution.

Other surfaces may do the same.

Stan Alekman
847-358-6975

Back to the Top

On 22 May 1999 at 22:37:54, "Edward F. O'Connor" (efoconnor.at.snet.net) sent the message


try using an closely erlated analog of the compound you're using, if that is
not possible try using a compound that shares the same characteristics (pK,
LogP).  try adjusting pH/organic to limit interaction--, try plastics.

Back to the Top

Want to post a follow-up message on this topic? If this link does not work with your browser send a follow-up message to PharmPK@boomer.org with "LC/MS/MS vial adsorption problem" as the subject

PharmPK Discussion List Archive Index page