Mass spectrometry (MS) is rapidly becoming a fundamental tool for biologists and biochemists in their efforts to
characterize cellular function. Recent advancements in MS technology and front-end methodologies, along with the completion
of the human genome have greatly popularized its use by researchers for protein identification and characterization. This paper is
a general overview of how mass spectrometry is being used for the analysis of peptides and proteins, focusing on its application
to molecular weight determination. Sample preparatory and cleanup techniques used in our laboratory for protein and peptide
analysis are provided, along with a discussion of data interpretation.