This application note describes a high sensitivity LC-MS quantification of a protein biomarker.
LC-MS is widely accepted for protein quantification for use in clinical research. However, this workflow can be complex and time consuming, often taking 24 hours to achieve analytically sensitive and accurate quantification. Using ProteinWorks eXpress Digest and ProteinWorks μElution SPE Clean-Up Kits, accurate quantification over 3.5 orders of magnitude (0.1–500 μg/mL) was readily achieved. The digestion time in this work is only 2 hours, which is 9X faster than previously published LC-MS methodologies.3 The analytical sensitivity represents a 50X improvement over earlier LC-MS methods and accurately quantifies low endogenous levels in urine while approaching the analytical sensitivity of immunoassays.