title: Analysis of residual monomers in dendritic methacrylate copolymers and composites by HPLC and headspace-GC/MS.
abstract: OBJECTIVE
  The aim of this study was to analyze the residual monomer content of photopolymerized dendritic methacrylate copolymers and particulate filler composites. Headspace-gas chromatography/mass spectrometry (HS-GC/MS) was compared with high performance liquid chromatography (HPLC).
  
  
  METHODS
  The resin mixtures consisted of a dendritic methacrylate monomer, methyl methacrylate and acetoacetoxyethyl methacrylate in varied proportions. In addition, one of the composites contained 1,4-butanediol dimethacrylate. Camphorquinone and 2-(N,N-dimethylamino)ethyl methacrylate were used as the light-activated initiator system. The content of residual methyl methacrylate and acetoacetoxyethyl methacrylate after 40 s photopolymerization were analyzed with HPLC and HS-GC/MS.
  
  
  RESULTS
  The content of residual methyl methacrylate decreased and residual acetoacetoxyethyl methacrylate increased with increasing concentration of acetoacetoxyethyl methacrylate in the resin mixture. The results with both methods had the same trend.
  
  
  CONCLUSIONS
  The addition of acetoacetoxyethyl methacrylate enhanced the copolymerization of methyl methacrylate, but did not decrease the total residual monomer content. The HS-GC/MS method was found to be a feasible method in the analysis of low-boiling residuals in dental polymers.
authors.affiliation: Department of Prosthetic Dentistry and Biomaterials Science, University of Turku, Institute of Dentistry, Lemminkäisenkatu 2, FI-20520 Turku, Finland. eeva.viljanen@utu.fi
authors.forename: Eeva K
authors.initials: EK
authors.lastname: Viljanen
authors.forename: Sarka
authors.initials: S
authors.lastname: Langer
authors.forename: Mikael
authors.initials: M
authors.lastname: Skrifvars
authors.forename: Pekka K
authors.initials: PK
authors.lastname: Vallittu
mesh_terms: D002851:Chromatography, High Pressure Liquid; D003188:Composite Resins / Q000737:chemistry*; D050091:Dendrimers / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D008689:Methacrylates / Q000032:analysis; D020366:Methylmethacrylate / Q000032:analysis*; D008768:Methylmethacrylates / Q000032:analysis*; D044367:Phase Transition; D011109:Polymethacrylic Acids / Q000737:chemistry*
chemical_list: D003188:Composite Resins; D050091:Dendrimers; D008689:Methacrylates; D008768:Methylmethacrylates; D011109:Polymethacrylic Acids; D020366:Methylmethacrylate; C009931:poly(ethylmethacrylate); C102737:1,4-butanediol dimethacrylate