Hand Sanitizer Spray

zeeshanzeeshan Member, PCF student
Hi All,

I am formulating a hand sanitizer spray but the overall pH is too high. Approx 9. How can I reduce the pH? The formula in weight is as follows:

Denatured Alcohol (96.11%) - 59.00
Water - 17.00
Isopropyl Alcohol - 5.00
Glycerine - 2.00
Propylene Glycol - 1.00
Isopropyl Myristate [IPM] - 1.00
Triethanolamine [TEA] (99%) - 0.75

Is the TEA required? I noticed the IPM "floating" at the top of the solution until I added the TEA. Can I use Polysorbate 20 to incorporate the IPM?

Comments

  • PerryPerry Administrator, Professional Chemist
    TEA is typically added to neutralize the Carbomer gelling agent. Since you don't have that in your formula, I don't think you need it. It also is causing the pH to increase.
  • Chemist77Chemist77 Member, PCF student
    And remove the IPM too, it will keep floating for nothing.
  • I have made hand sanitizer with isopropyl alcohol and aloe Vera gel but it is cloudy does this effect the use?
  • zeeshanzeeshan Member, PCF student
    Thank you for the prompt replies @Perry and @Chemist77. I will omit the TEA and IPM.

    I am also trying to formulate a gel version of the same, but the gel is too watery. The formula in weight is as follows:

    Denatured Alcohol (96.11%) - 59.00
    Water - 17.00
    Glycerine - 2.00
    Propylene Glycol - 1.00
    Isopropyl Myristate [IPM] - 1.00
    Triethanolamine [TEA] (99%) - 2.5
    Acrylates/C10-30 Alkyl Acrylate Crosspolymer (Ashland Ultrathix 21) - 0.35

    I have also tried adding IPA but as soon as I neutralize, the mixture gets cloudy and a white powder settles at the bottom. I read that TEA works with a maximum of 60% alcohol by weight. 

    I'm struggling with the Ultrathix 21 and TEA quantities / ration to get a thick and clear gel. The IPM can be omitted as well.

    I've been asked to incorporate Tea Tree Oil well as a 'fragrance' but I want to get a stable product first before adding anything else. 

    Appreciate any feedback. Thank you.
  • PharmaPharma Member, Pharmacist
    zeeshan said:
    ...
    Triethanolamine [TEA] (99%) - 2.5
    Acrylates/C10-30 Alkyl Acrylate Crosspolymer (Ashland Ultrathix 21) - 0.35...
    I may be wrong but the proportion TEA/UltraThix doesn't sound right. 7 times more base than polymer for neutralisation? Try adding just enough TEA to obtain a neutral pH (around 7). I have to guess how much TEA you'd actually need but my gut feeling tells me it has to be around 10 times less than what you use i.e. around 0.25.
  • zeeshanzeeshan Member, PCF student
    edited March 20
    Pharma said:
    zeeshan said:
    ...
    Triethanolamine [TEA] (99%) - 2.5
    Acrylates/C10-30 Alkyl Acrylate Crosspolymer (Ashland Ultrathix 21) - 0.35...
    I may be wrong but the proportion TEA/UltraThix doesn't sound right. 7 times more base than polymer for neutralisation? Try adding just enough TEA to obtain a neutral pH (around 7). I have to guess how much TEA you'd actually need but my gut feeling tells me it has to be around 10 times less than what you use i.e. around 0.25.
    Thank you for the feedback. I have reduced the TEA significantly and I am seeing much better results. I'm going with a TEA to UltraThix ratio of about 1.2:1.
  • Chemist77Chemist77 Member, PCF student
    That's the recommended ratio as posted by many here, check the Lubrizol sheet on neutralisation ratios. 
  • zeeshanzeeshan Member, PCF student
    Chemist77 said:
    That's the recommended ratio as posted by many here, check the Lubrizol sheet on neutralisation ratios. 
    Yes, I have read that after a few failed attempts. I had miscalculated the dosage. I was given a recommended dosage of 1.5-2.4%, but of a 10% solution. I went with a direct 2% dose of TEA  :#
  • em88em88 Member
    Way too much TEA! 
    Check the pH!!! 
  • chemicalmattchemicalmatt Member, Professional Chemist
    Suggested ratio of Triethanolamine 99%: Ultrez 21 will be 1:1 no more.  That Ashland stuff is relabeled Ultrez.
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