This standard is a complex mixture of peptides produced by the tryptic digest of reduced and alkylated Bovine Serum Albumin (BSA). This peptide mixture can be used to test a Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight (MALDI-TOF) or Electrospray Ionization (ESI) mass spectrometer (TOF, Q-TOF or Ion Trap).