Patent ID: 7837871

Claim:
A pipet tip column for extracting an analyte comprising: i) a column body having an open upper end, an open lower end, and an open channel between the upper and lower ends of the column body; ii) a bottom frit extending across the open channel, wherein the bottom frit is located at the open lower end of the column body; iii) a top frit extending across the open channel between the bottom frit and the open upper end of the column body, wherein the top frit or the bottom frit material is selected from a group consisting of polyamide, polycarbonate, cellulose, nitrocellulose, cellulose acetate, polyvinylidine difluoride, polytetrafluoroethylene, polypropylene, polysulfone, metal, glass, nylon and polyester, wherein the top frit, bottom frit, and column body define an extraction media chamber; and iv) a packed bed of hydrated gel resin positioned inside the extraction media chamber, wherein the gel resin is agarose or sepharose, wherein the bed is not tightly packed, and wherein said pipet tip column is characterized by a back pressure in the range of about 0.01 psi to 1.5 psi when an aqueous solution is passed through the column at a flow rate of 1 ml/min.