Device for solid phase extraction and method for purifying samples prior to analysis

1. A method of separating a target substance from interfering components in a sample medium comprising:

providing an solid phase extraction device (SPE) comprising a reservoir with an opening for receiving fluids; a well comprising an internally tapered wall, the well having a wider interior diameter at a first end closest to the reservoir than at a second end close to an exit spout, the well for conducting an extraction; an exit spout at the second end of the well for discharging fluids; a first filter press sealed between the internally tapered walls of the well for retaining insoluble components of the fluids; a second filter having a smaller diameter than the first filter press-sealed between the internally tapered walls of the well spaced apart and toward the exit spout from the first filter; a quantity of sorbent particles partial filing the volume in the well between the first and second filters; and a void volume between the quantity of sorbent particles and the first filter for separating the quantity of sorbent particles from the first filter; and

substantially isolating a target substance using the solid phase extraction device.

2. The method according to claim 1 wherein:

the mass of sorbent particles is less than 5 milligrams.

3. The method according to claim 1 wherein the isolating step comprises the steps of:

conditioning the SPE device with an organic solvent;

equilibrating the SPE device with an aqueous solution;

adding a prepared sample containing the target substances and interfering components to the SPE device;

washing the SPE device with an aqueous-organic solution to remove interfering components; and

eluting the adsorbed target substances.

4. The method according to claim 3 wherein:

the target substance is substantially eluted in less than 50 μL volume.

5. The method according to claim 3 further comprising:

diluting the eluted target substances by passing a diluent through the solid phase extraction device.

6. The method according to claim 1 where the sample medium is blood plasma, urine or serum.

7. The method according to of claim 1 where the target substance comprises at least one polar compound, non-polar compound, acidic compound, neutral compound, biopolymer, basic compounds, and mixtures thereof.

8. The method of claim 1 where greater than 80% of each absorbed target substances is isolated in at most 50 μL volume.

9. The method according to claim 1 wherein the sorbent particles comprise an ion exchange sorbent; a reversed phase sorbent; or a normal phase sorbent.

10. A method of separating a target substance from interfering components in a sample medium as in claim 1 further comprising:

the reservoir and well in a multi-well array.