FINGERPRINT ANALYSIS OF INSULIN - APPLICATION IN STABILITY STUDIES OFPHARMACEUTICAL PREPARATIONS

The identification of a protein drug and the determination of its puri ty requires the use of several analytical methods. One identification probe used is the proteolysis of insulin with Staphylococcus aureus pr otease. This method yields a characteristic pattern of peptide fragmen ts (''fingerprint'') which could be separated by reverse-phase high-pe rformance liquid chromatography (HPLC) with gradient elution and ultra violet detection. This probe could be used as a stability-indicating m ethod for peptide and proteins, supplementing other traditional method s as reverse-phase (RP) and size-exclusion (SE) HPLC. Proteolysis of c ommercial human insulin preparations stored under different conditions produces modified fingerprints versus reference standard digested sam ples. Results vary as a function of the type of preparation and storag e conditions since the degradation products detected by SE-HPLC are di fferent.