title: Does Para-chloroaniline Really Form after Mixing Sodium Hypochlorite and Chlorhexidine?
abstract: BACKGROUND
  Mixing sodium hypochlorite (NaOCl) with chlorhexidine (CHX) forms a brown-colored precipitate. Previous studies are not in agreement whether this precipitate contains para-chloroaniline (PCA). Tests used for analysis may demonstrate different outcomes. Purpose of this study was to determine whether PCA is formed through the reaction of mixing NaOCl and CHX by using high performance liquid chromatography, proton nuclear magnetic resonance spectroscopy, gas chromatography, thin layer chromatography, infrared spectroscopy, and gas chromatography/mass spectrometry.
  
  
  METHODS
  To obtain a brown precipitate, 4.99% NaOCl was mixed with 2.0% CHX. This brown precipitate was analyzed and compared with signals obtained from commercially available 4.99% NaOCl, 2% solutions, and 98% PCA in powder form.
  
  
  RESULTS
  Chromatographic and spectroscopic analyses showed that brown precipitate does not contain free PCA.
  
  
  CONCLUSIONS
  This study will be a cutoff proof for the argument on PCA formation from reaction of CHX and NaOCl.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Eskişehir Osmangazi University, Eskişehir, Turkey. Electronic address: ekimorhan@ogu.edu.tr.
authors.forename: Ekim Onur
authors.initials: EO
authors.lastname: Orhan
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, Eskişehir Osmangazi University, Eskişehir, Turkey.
authors.forename: Özgür
authors.initials: Ö
authors.lastname: Irmak
authors.affiliation: Department of Chemistry, Faculty of Science, Anadolu University, Eskişehir, Turkey.
authors.forename: Deniz
authors.initials: D
authors.lastname: Hür
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, Eskişehir Osmangazi University, Eskişehir, Turkey.
authors.forename: Batu Can
authors.initials: BC
authors.lastname: Yaman
authors.affiliation: Department of Endodontics, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Bekir
authors.initials: B
authors.lastname: Karabucak
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D011232:Chemical Precipitation; D002710:Chlorhexidine / Q000008:administration & dosage; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004347:Drug Interactions; D008401:Gas Chromatography-Mass Spectrometry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D012388:Root Canal Irrigants / Q000737:chemistry; D012973:Sodium Hypochlorite / Q000737:chemistry*
chemical_list: D000814:Aniline Compounds; D012388:Root Canal Irrigants; D012973:Sodium Hypochlorite; D002710:Chlorhexidine; C004658:4-chloroaniline
keywords: Brown precipitate; chlorhexidine; interaction; irrigants; nuclear magnetic resonance; para-chloroaniline; sodium hypochlorite