What is a Quat Sanitizer?
Quaternary ammonium compounds are permanently charged cations with four aryl or alkyl side groups. See benzalkonium chloride
as an example. Quats are effective against bacteria, amoebas, fungi, enveloped viruses & invertebrate larvae because they disrupt cell membranes at levels as low at 200ppm.
- Work best in the pH range of 8-11.
- Lose potency in hard water (see hard water test strips).
- Color charts start to deviate at 45C (110F) & above.
- Not sporocidal or effective against hydrophilic viruses.
- Cotton and gauze pads can absorb & reduce effectiveness (quat binding).
Quat binding is where positively charged quaternary ammonium chloride ions are absorbed into negatively charged natural textile fabrics. As much as 50% of the quat disinfectant can be removed from solution after just 10 minutes.
The best work around to quat binding is to use higher concentrations of disinfectant which is what the 0-1500ppm Indigo™ quat test strips were designed to handle.
Note: All Indigo™ quat test strips are Made in USA & and are Q/A'd against NIST standards.
The dilution calculator will work with any quat but each has slightly different chemical properties. You may have to do a test strip calibration to get reproducible results. Your Quat supplier should be able to help you.
Here are some common quats used in sanitizer sprays, mouth washes, boot baths, etc. Click on the highlighted compounds to examples of quaternary ammonium structures.
How to Dilute Quaternary Ammonium Compounds
disinfectants are formulated with more than one quaternary ammonium compound & may be designated as "multi-quats". Indigo™ test strips are calibrated for Oasis 146 consisting of:
To dilute any multi-quat accurately, add up the percentages of the quats used in the formulation. For Oasis 146, they add up to 7.5%. Use this percentage in our Dilution Equation Calculator
to prepare a 1L/1US quart spray bottle as in this example
Step 1: enter 7.5%.
Step 2: enter 1500ppm as the desired final concentration
Step 3: enter 1000mL (=1L, =~1 US quart) for the amount of water
Step 4: press Calculate to see that 20mL (~1 oz) of quat added to the 1L of water (0.98L to be really precise) gives you a 1500ppm solution.
If you're good with math, you can check these results. First. converting 7.5% to 75000ppm. Then 1500ppm divided by 75000ppm equals 1/50 which is the same ratio as 20mL/1000mL.
Not clear on percent vs ppm? See our blog: Diluting Chlorine, Peroxide or Quat Sanitizers is Easy