title: Chemical analysis of solid-state irradiated human insulin.
abstract: OBJECTIVE
  To study the chemical modifications induced upon irradiation of solid human insulin at radiosterilization doses and investigate the influence of the absorbed dose on radiolysis.
  
  
  METHODS
  Volatile radiolytic products were monitored by gas chromatography coupled with mass spectrometry (GC-MS) and non-volatile products by two different high performance liquid chromatography (HPLC) methods: the formation of higher molecular weight proteins was assessed by size exclusion liquid chromatography whereas assays for related compounds and chemical potency tests were carried out using reverse-phase HPLC-UV. Conformational changes were investigated by measurements of circular dichroism.
  
  
  RESULTS
  After gamma irradiation at 10 kGy, the recovery of insulin was 96.8%; higher molecular weight proteins accounted for 0.35% (relative peak area) and other related compounds (including A21 desamido insulin) represented 1.29%. No major structural changes and no volatile radiolytic compounds were detected.
  
  
  CONCLUSIONS
  Human insulin samples irradiated in the solid-state at 10 kGy (gamma rays) and 14 kGy (electron-beam) meet the European Pharmacopoeia requirements and can be considered as quite stable towards radiation from a chemical analysis viewpoint.
authors.affiliation: Laboratory of Chemical and Physicochemical Analysis of Drugs (CHAM), Université Catholique de Louvain, CHAM 72.30, Avenue E. Mounier, 72, B- 1200, Brussels, Belgium. helene.terryn@cham.ucl.ac.be
authors.forename: Hélène
authors.initials: H
authors.lastname: Terryn
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Vanhelleputte
authors.forename: Aubert
authors.initials: A
authors.lastname: Maquille
authors.forename: Bernard
authors.initials: B
authors.lastname: Tilquin
mesh_terms: D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D005720:Gamma Rays; D008401:Gas Chromatography-Mass Spectrometry; D007004:Hypoglycemic Agents / Q000032:analysis* / Q000528:radiation effects*; D007328:Insulin / Q000032:analysis* / Q000528:radiation effects*; D008968:Molecular Conformation; D008970:Molecular Weight; D019265:Spectroscopy, Near-Infrared; D014835:Volatilization
chemical_list: D007004:Hypoglycemic Agents; D007328:Insulin