Interaction between chlorhexidine digluconate and EDTA

J Endod. 2008 Dec;34(12):1521-3. doi: 10.1016/j.joen.2008.08.039. Epub 2008 Oct 11.

Abstract

The combination of chlorhexidine and EDTA produces a white precipitate. The aim of this study was to determine if the precipitate involves the chemical degradation of chlorhexidine. The precipitate was produced and redissolved in a known amount of dilute trifluoroacetic acid. The amount of chlorhexidine and EDTA present in the dissolved precipitate was determined by reverse-phase high performance liquid chromatography (HPLC) with ultraviolet detection at 288 nm. More than 90% of the precipitate's mass was found to be EDTA or chlorhexidine. The remainder is suspected to be water, gluconate, and sodium. Parachloroaniline, a potentially carcinogenic decomposition product of chlorhexidine, was not detected in the precipitate (the limit of detection was 1%). The molar ratio of chlorhexidine to EDTA in the precipitate was about 1.6 to 1. Based on the results, chlorhexidine forms a salt with EDTA rather than undergoing a chemical reaction.

MeSH terms

  • Aniline Compounds / chemistry
  • Chelating Agents / chemistry*
  • Chemical Precipitation
  • Chlorhexidine / analogs & derivatives*
  • Chlorhexidine / chemistry
  • Chromatography, High Pressure Liquid
  • Edetic Acid / chemistry*
  • Gluconates / chemistry
  • Humans
  • Materials Testing
  • Root Canal Irrigants / chemistry*
  • Sodium / chemistry
  • Solubility
  • Solvents / chemistry
  • Trifluoroacetic Acid / chemistry
  • Water / chemistry

Substances

  • Aniline Compounds
  • Chelating Agents
  • Gluconates
  • Root Canal Irrigants
  • Solvents
  • Water
  • Edetic Acid
  • Sodium
  • Trifluoroacetic Acid
  • chlorhexidine gluconate
  • Chlorhexidine
  • gluconic acid
  • 4-chloroaniline