title: An in vitro spectroscopic analysis to determine the chemical composition of the precipitate formed by mixing sodium hypochlorite and chlorhexidine.
abstract: BACKGROUND
  The purpose of this in vitro study was to determine the chemical composition of the precipitate formed by mixing sodium hypochlorite (NaOCl) and chlorhexidine (CHX) and the relative molecular weight of the components.
  
  
  METHODS
  Using commercially available CHX gluconate, a 2% solution was formed and mixed in a 1:1 ratio with commercially available NaOCl producing a brown precipitate. The precipitate as well as a mixture of precipitate and pure CHX diacetate was then analyzed using one-dimensional and two-dimensional NMR spectroscopy.
  
  
  RESULTS
  The one-dimensional and two-dimensional NMR spectra were fully assigned in terms of chemical shifts of all proton and carbon atoms in intact CHX. This permitted identification of two major CHX breakdown products, neither of which are parachloroaniline (PCA). Both products are related to PCA in that they are parasubstituted benzene compounds. Based on NMR data and a proposed mechanism of CHX breakdown, the products appear to be parachlorophenylurea (PCU) and parachlorophenylguanidyl-1,6-diguanidyl-hexane (PCGH).
  
  
  CONCLUSIONS
  Based on this in vitro study, the precipitate formed by NaOCl and CHX is composed of at least two separate molecules, all of which are smaller in size than CHX. Along with native CHX, the precipitate contains two chemical fragments derived from CHX (PCU and PCGH), neither of which are PCA.
authors.affiliation: Department of Endodontics, Marquette University School of Dentistry, Milwaukee, WI53233, USA. Nowicks03@gmail.com
authors.forename: James B
authors.initials: JB
authors.lastname: Nowicki
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Sem
mesh_terms: D000814:Aniline Compounds / Q000032:analysis; D055598:Chemical Phenomena; D002710:Chlorhexidine / Q000737:chemistry*; D012973:Sodium Hypochlorite / Q000737:chemistry*; D013057:Spectrum Analysis
chemical_list: D000814:Aniline Compounds; D012973:Sodium Hypochlorite; D002710:Chlorhexidine