The invention provides methods of monitoring the production of a target polypeptide by generating surface enhanced laser desorption/ionization mass spectral profiles of samples taken from multiple cell culture batches or of samples taken at different times from a given batch. The invention additionally provides methods for monitoring the purification of a target polypeptide from a mixture by generating surface enhanced laser desorption/ionization mass spectral profiles of samples taken at various times during a purification process. In addition, the invention relates to methods of identifying conditions that can be used in increasing the scale of a given purification process.