The 96-well protein precipitation filter ideal for removing precipitated proteins from biological plasma/serum. The plate consists of a 0.2 μm hydrophobic graded filte/frit. Biological plasma is first added to the 96-well plate followed by a protein preciitating agent (e.g., acetonitrile). After a brief mixing step, vacuum is applied to the plate, and the filter/frit removes precipitated proteins from the sample. The resulting filtrate is ready further processing and/or analysis.