The previous edition of this book included a brief discussion of more classical techniques for peptide purification such as two-dimensional electrophoresis and thin-layer chromatography. Although there is still some use of these techniques, almost all of the work since 1984 has focused on HPLC or specialized affinity approaches. It is not possible to discuss the current status of peptide purification in any depth, and the reader is directed toward several reference works for further detail.1-11