Cleaning Validation Sal Acid & Menthol

I am working on 2 cleaning validations for Salicylic Acid and Menthol and am having a hard time determining what to use on some swabs to see if the actives are still in the tank.  It looks like both Sal Acid and Menthol in Alcohol and Acetone so I am thinking I can use one of those materials on the swabs to then see if the tank is clean.  Is there a better option?


  • Our validation  for menthol is extremely simple (and SGS were happy to approve it)

    Once cleaning has been complete, we collect the final rinse water and take it to the lab- and smell it.

    Menthol is so strong it is detectable in quite small quantities and any residual menthol is detectable.

  • chemicalmattchemicalmatt Member, Professional Chemist
    edited December 2019
    @Herbnerd, that is really cool for menthol detection, and pun intended! Salicylic acid qualitative should be easy, just swab a ferric chloride dilute solution and if it turns purple you are SalAc positive, if not, negative. Place into a spectrophotometer (visible spectrum) cuvette for an absorbance number if that is critical.
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