Question about Preservatives/Chelators

Hi everyone!

A question: is silver citrate + gluconolactone + leucidal liquid a stable preservative that can work for any water-based formulation? (Assume pH is 3.5-6)

Similarly, is sodium phytate + gluconolactone a strong enough chelator for the conditions above?

Thank you in advance!


  • lewhitaklewhitak Member
    Hello Wickers!
    Unfortunately, no preservative system is a total fit for all water-based formulas. Every preservative needs to be evaluated based on the other materials present. Typically a PET is the best thing for evaluating new preservative systems in formulas to ensure efficacy.

    For instance, Silver Citrate can be incompatible with cellulose polymers (HEC), some starches, and cationic ingredients.

    Gluconolactone causes pH drift downwards--which if you're not careful will knock you out of your preservative's effective range. Sodium phytate is similar in that the effectiveness is pH dependent. 

    Leucidal liquid is a "mild" antimicrobial at best, and a gamble of a preservative at worst. If you search through the forum for this material you will get much more information. Personally, I don't use any of these materials because they aren't the most robust. 

    If you have a lot of bug "food" present in the form of various additives in a formula you are going to need to pay close attention to your preservative and also to lowering water activity. These types of formulas are hard to preserve.
  • lewhitaklewhitak Member
    Here is a good thread to reference, especially for information on the chelator:
  • In our lab, we usually use chlorphenesin. It is water soluble, very reliable and convenient.

    For your information.

    Main component: 3-(4-chlorophenoxy)-1, 2-propanediol
    CAS: 104-29-0
    Molecular formula: C9H11ClO3
    Melting point: 77-79°C
    Boiling point : 369.5ºC at 760mmHg
    Suggested usage amount: 0.1-0.3%
  • WickersWickers Member
    Thank you!

    For a pH of ~4-6, is gluconolactone and chlorphenesin OK to use together? 
    Any incompatibilities with possible ingredient types I should be aware of?

    Thank you once again. 
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