John Griffiths is an analytical chemist with 30 years experience in the analysis of a wide range of analytes using mass spectrometry and other techniques. For the past 13 years, John has focused solely on the application of mass spectrometry to the analysis of peptides and proteins – proteomics. John has published multiple papers on biological mass spectrometry and has presented his work at both national and international conferences. John has a particular interest in the analysis of PTMs and has developed a number of strategies, such as the MIDAS with Richard Unwin, to enhance their detection. John is also the director of a mass spectrometry training and consultancy enterprise, MS-Insight Ltd. Richard Unwin is a biochemist and mass spectrometrist with over 18 years’ experience in the field of proteomics, in particular the quantification and characterization of proteins by mass spectrometry. Richard was among the first to develop the use of iTRAQ technology for protein quantitation and, with John Griffiths, was also amongst the first researchers to begin to realize the potential of multiple reaction monitoring MS for the discovery and characterization of post-translational modifications. Richard has contributed chapters on proteomics methods for a number of textbooks, aimed at both practicing mass spectrometrists and undergraduates, and has authored over 40 papers in the field.