Metformin exctraction from human plasma

[Bhuvaneswaran]

Any one can please help me to find out the method for Metformin exctraction from human plasma .

[AA]

Determination of metformin and phenformin in human plasma and urine by reversed-phase HPLC
Benzi, L. , et al
J. Chromatogr. / Year: 1986 / Volume: 375 / Page: 184

[Bhuvaneswaran]

Actually i want the exctraction of metformin from human plasma for lc-ms/ms analysis [/code][/list]

[AA]

Perhaps you could read the paper, learn how to do the extraction and modify the LC method to be compatible with LC/MS.

[Kostas Petritis]

Bhuvaneswaran,

As AA implied the extraction method should have worked for LC-MS as well. In general old extraction methods that have been developed for UV should work for MS as well as normally there is less extraction needed for LC-MS.

Having said that, I do not really like to try to reproduce very old methods, basically because 1) you can not find the LC columns anymore and/or 2) new stationary phases are much more pure and contains much less silca residues due to better alkyl bonding and end-capping.

Actually, although I have never worked with metformin, the name sounded familiar. The reason is due to an article published in chromatographia some time ago:

Title: LC phases improve, but not all assays do: Metformin bioanalysis revisited
Author(s): van de Merbel NC, Wilkens G, Fowles S, Oosterhuis B, Jonkman JHG
Source: CHROMATOGRAPHIA 47 (9-10): 542-546 MAY 1998.

The authors refer to two methods, the old one could not be reproduced the new one could. The reason that the old one could not be reproduced was that while the separation mechanism was solely attributed to ion-pairing chromatography, the residual silica was heavily participating in the separation/retention of this compound.

As a result, in general, I find it of marginal utility to look at application oriented references of 15 years old or more (note that I said about application oriented and not fundamentals). However, if there is nothing in recent years about my compound, I would probably use old publications as a start...

[shirishpatel]

Metformin HCl is highly water soluble and it will not retain on any Reverse phase Mechanism .

You use Ion exchange Mechanism , Use stationary phase with SO3H ends so Metformin will retain on it and you can elute out with the use of methanol or Acetonitrile

[Uwe Neue]

Copy from another post:

Here is a generic procedure useful for basic drugs with Oasis MCX sample preparation devices. It has been tested over and over again with many different compounds and results in a rather clean extract.

Sample preparation:
1. Acidify your plasma sample, filter or centrifuge, then add the internal standard that you choose.
2. Use an Oasis MCX cartridge or 96-well plate. The exact volume for any of the steps depends on the volume of the device that you select.
3. Activate the SPE device by adding methanol, followed by acidified water (use the same acid as used to acidify you sample).
4. Load the sample onto the SPE device
5. Wash the sample clean by using 1% formic acid in methanol.
6. Extract your analyte from the cartridge using at least 1% ammonia in methanol (if the recovery is not 100%, increase the ammonia concentration.

[Chris Pohl]

shirishpatel,

I'm puzzled! You describe a separation based on cation-exchange but an eluent system devoid of any electrolyte! Are you sure you have this description correct?