Sample Prep

[chtdanny]

Hi, i am extracting a steroid like drug from human serum.
The structure of the drug look like Testosterone, but it has a long fat chain on the 4th ring.

I used a lot of different solvents (MTBE, HEXANE, Ethyl Acetate), but the recovery rate is so low.

However, i used charcoal treated serum to make my standard curve, after the extraction, the signals are good, but when i extracted it from the human serum (sample), the signal drop.

Any suggestion ??

Many thanks!!!

[Don_Hilton]

I would expect that the charcoal treated serum has removed many non-polar compunds that, when present, either interfere with yoru detection or help hold your target compund into solution.

Make an extract of your human serum and spike the extract rather than the sample. This will help you determine if the problem is in the extraction or in the workup and chromatography after the extraction. (Good recovery - you know the spike travels through the subsequent steps. Poor recovery - you know that the spike disappeared between spiking and detection.)

[Alp]

Phospholipids are known to cause ionization suppression, perhaps the charcol removes them from the serum. Is there a way to remove phospholipids from plasma/serum?

What's your retention time like? Coming out in a mountain of junk?

Have you researched a solid phase extraction method? It might be cleaner than Liq/Liq.

Alp