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

1. A method of providing for a range of sorbent masses within a solid phase

extraction device comprising:

providing an solid phase extraction device 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

adjusting the filter diameters whereby the filters settle in different positions within the tapered well.

2. The method of providing for a range of sorbent masses within a solid phase extraction device as in claim 1 further comprising:

the reservoir and well in a multi-well array.

3. A method of making an extraction device comprising:

providing a housing having a reservoir with an opening for receiving fluids and a well having a wall that tapers at an included angle of between 1 and 30° with an exit spout at a narrow end of the well and an opening at a wide end of the well, the well including a lower diameter of an inverted conical frustum that provides a specified aspect ratio when a selected volume of sorbent particles are placed in the well at that lower diameter;

placing a smaller spherical filter with a diameter equal to the lower diameter in the well;

placing the selected volume of sorbent particles in the well; and

placing a larger spherical filter, with a diameter sufficiently large to position it above a void volume above the volume of sorbent particles, in the well.

4. The method of claim 3 wherein after the smaller spherical filter is placed in the well, it is pressed in place.

5. The method of claim 3 wherein after the larger spherical filter is placed in the well, it is pressed in place.

6. The method of claim 3 wherein the volume of sorbent particles is placed in the well by pouring a slurry containing the volume of sorbent particles into the well and allowing the liquid to exit through the exit spout.

7. The method of claim 3 wherein the filters are placed in the well by dropping them into the well and allowing them to find a seating point.

8. A method of making an extraction device comprising:

providing a housing having a reservoir with an opening for receiving fluids and a well having a wall that tapers at an included angle of between 1 and 30° with an exit spout at a narrow end of the well and an opening at a wide end of the well, the well including the lower diameter of an inverted conical frustum that provides a specified aspect ratio when a selected volume of sorbent particles are placed in the well at that lower diameter;

press sealing a spherical filter with a diameter equal to the lower diameter in the well;

placing the volume of sorbent particles in the well; and

press sealing a second spherical filter, with a diameter sufficiently large to position it above a void volume above the volume of sorbent particles, in the well.