Automated protein precipitation and/or dispersive solid phase extraction using filter tips
Devices and methods for performing pre-analysis sample processing of biological and chemical samples using robotic liquid handlers are disclosed. Methods for solid phase extraction, protein precipitation and filtration of biological and chemical samples using automation and the devices in a rapid and convenient way are described.
1. A method of automated filtering of a solution, comprising:
a) introducing a sample solution comprising at least one target compound into a first sample well on a robotic liquid handler sample tray;
b) aspirating said sample solution from said first sample well into a top pipette tip, wherein said top pipette tip is a wide bore;
c) moving said top pipette tip to a pipette tray having at least one filter pipette tip, wherein the filter pipette tip contains at least one screen or porous frit inside the filter pipette top located at a distal delivery end opposite of a hub;
d) inserting and fitting said top pipette tip containing said sample solution into said filter pipette tip, such that an air tight seal is made below said hub of said filter pipette tip;
e) moving said top pipette tip and filter pipette tip as a single piece to a second sample well; and,
f) dispensing said sample solution through said filter pipette tip into said a second sample well to form a filtered solution, wherein said filtered solution has said at least one target compound and moving said top pipette tip and filter pipette tip as a single piece to a waste bin.
2. The method of claim 1 , further comprising step g) extracting said filtered solution using solid phase or liquid-liquid extraction.
3. The method of claim 1 , further comprising step g) injecting said filtered solution into an analytical instrument.
4. The method of claim 1 , further comprising step g) extracting said filtered solution using solid phase or liquid-liquid extraction, and step h) injecting said extracted filtered solution into an analytical instrument.
5. The method of claim 1 , wherein said filter pipette tip contains a substrate above said screen or porous frit, wherein said substrate is chosen from a group comprising resin, polymeric sorbent, glass wool, fibrous material, silica or combinations thereof.
6. The method of claim 1 , wherein said filter pipette tip comprises a gasket on its inner surface at or below said hub, wherein said top pipette tip contacts said gasket to form said air-tight seal and wherein said top pipette tip does not pierce said at least one screen or porous frit.
7. The method of claim 1 , wherein the sample solution is a protein-precipitated biological sample.
8. The method of claim 1 , further comprising an automated protein precipitation process performed before step 1a, said protein precipitation process comprising:
a) introducing a biological sample containing protein and at least one target compound in said first sample well on said robotic liquid handler sample tray;
b) dispensing a precipitation reagent into said first sample well using a wide bore pipette tip attached to a motorized pipettor on a robotic liquid handler; and,
c) mixing said precipitation reagent and biological sample by repeatedly aspirating and dispensing said precipitation reagent and biological sample with said wide bore pipette tip to form a protein precipitate and a protein-precipitated biological sample, wherein said supernatant of protein-precipitated biological sample is substantially free of protein and contains at least one target compound.
9. The method of claim 8 , wherein said biological sample is selected from the group comprising serum, plasma, whole blood, urine, spinal fluid, meconium and tissue homogenate.