Cefdinir Plasma extraction method

[sandip.gurav]

Presentely i m working on cefdinir(antibiotic) which is acidic in nature.
The plasma extraction method i've tried is acidification ( with acetic acid )of plasma followed by deproteinisation with ACN. Drug is extracted but the broad peak were observed, i try to improve it by increasing acid concentration but no change in peak shape.

Could any one suggest cause behind this.

[Uwe Neue]

There could be a multitude of issues...

What is your mobile phase and column?

Is the broad peak your drug peak or junk?

How much acetonitrile is in the sample?

Depending on your answers, several things are possible. The peak could be too wide because the the sample is injected in too much acetonitrile. It could be that other elements of your sample and mobile phase are incompaticle. It could be residual binding to protein. If I think more, I could possibly come up with a few more possible issues.

[sandip.gurav]

Dear Uwe

The problem has been sorted out by decreasing plasma volume from
500 µl to 200 µl and ACN from 800 µl to 1000 µl.

Mobile phase is ACN : 10 mM Ammonium acetate (60 :40)

[Uwe Neue]

This indicates that the sample cleanup was insufficient before.