Sodium benzoate vs benzoic acid efficacy

Is these any different between preservation efficacy of about %0.2 sodium benzoate or benzoic acid if used in combination with phenoxyethanol at the same pH? 


  • PhilGeisPhilGeis Member, Professional formulator
    Other than the lesser concentration of the ion due to the sodium salt, there is effectively no difference - assuming you obtain solution of addition.   It's a pH driven equilibrium.
  • @PhilGeis sorry buy i didn't get your point "assuming you obtain solution of addition". Can you explain it a bit more! 
  • PharmaPharma Member, Pharmacist
    Once you bring benzoic acid or sodium benzoate into solution and adjust to a given pH, equimolar concentrations of the two will have a virtually identical antimicrobial effect.
  • AbdullahAbdullah Member
    @Pharma got it thanks
  • PhilGeisPhilGeis Member, Professional formulator
    Benzoic acid solubility can be an issue.  it's much less soluble in  water than the sodium benzoate.  Other than that, there is no difference.
  • AbdullahAbdullah Member
    @PhilGeis thanks
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