Chromatography Forum

We have had good success cleaning up manure samples using a modification of the QuEChERS method. Briefly:

1) LL extract liquid manure with diethyl ether
2) Add graphitized black carbon, psa sorbent (a weak anion exchanger from Varian) and magnesium sulfate, then mix
3) filter
4) evaporate and reconstitute in methanol for LC/MS

So... you might want to look into graphitized black carbon and the QuEChERS method. We first tried a number of SPE methods, but nothing was as good as black carbon at removing the hydrophobic gunk present in manure extracts. The graphitized black carbon (Supelco) is much easier to work with than plain old black carbon. With plain black carbon, we got low recoveries for some hormones.

The problem is probably your gradient and nothing to do with your extraction. For what I do (extraction from plasma), phospholipids are almost a given at anytime so you have to optimize your LC front to move your peak off of where the phospholipids elute.

Determine the %B (Methanol) you need for the compound to start eluting and ramp your gradient to that point rather than the arbitrary 45-95%.

Try some different columns as well.