This protocol details steps to normalize the amount of protein for tryptic digestion in quantitative proteomic workflows by using a Biomek NX liquid handler system. It is optimized to normalize protein concentrations in a 96-well plate format and add TCEP, IAA, and trypsin. This protocol works best as part of a semi-automated proteomic sample preparation workflow with: Automated Chloroform-Methanol Protein Extraction on the Biomek-FX Liquid Handler System and Automated Protein Quantitation with the Biomek-FX liquid handler system