Quaternary Ammonium Disinfectant Compounds

Quaternary Ammonium Compound Test Strips

For disinfection & sanitizing in restaurants, hospitals, organic farming & more

Quaternary Ammonium Compound Test Strips

Indigo® quaternary ammonium compound test strips confirm optimal dilutions for disinfection & sanitizing in restaurants, hospitals, organic farming & more.

All come with 100 test strips/vial and a guaranteed 3 year minimum shelf life. Certificates of Analysis, Stability & SDS Statements are on-line; Certificates of Conformance available on request.

Buy Indigo® test strips, the brand you can trust for accuracy & technical support. Call us on our toll-free line for immediate assistance or e-mail us with your questions. 1 hour response is typical during business hours, M-F, slightly longer on weekends. Optional next business day delivery in any quantity of most items.

Exploring the Benefits of Quaternary Ammonium Disinfectants

QAC cationic surface activity interacts with the cytoplasmic membrane of bacteria and lipids of viruses. It is the positive electrical charge of Quats that effects especially long attachment times to the negatively charged regions of bacterial cell membranes. This can block channels that take up nutrients or excrete waste products, effectively starving or poisoning bacteria. They show considerable virucidal efficacy for inactivating enveloped viruses including coronaviruses such as SARS-CoV-2 which causes COVID-19. They work best in the pH 8-11, alkaline, range but activity can be reduced in hard water. Quats are also effective algal biocides & are used in industrial water systems to limit their growth. They can suppress Staphylococcus aureus to reduce transient bacterial skin contamination. Quats can also inactivate multidrug-resistant strains of vancomycin-resistant Entercoccus & Pseuodomonas aeruginosa from a variety of hard surfaces ranging from medical devices to computer keyboards in hospitals and optimize disinfection application in healthcare facilities in general. Newer quaternary ammonium compounds (4th generation) are dual twin-chain, also known as dialkyl. These include didecyl dimethyl ammonium bromide and dioctyl dimethyl ammonium bromide which and are stable/active in hard water and work in the presence of anionic residues.

Displaying 1 to 4 (of 4 products)
QAC QR Test Strips 0-400 ppm

QAC QR Test Strips 0-400 ppm

SKU: 33819-400
$8.95USD or lower Each
Quat Sanitizer Test Strips-High Level 1500ppm

Quat Sanitizer Test Strips-High Level 1500ppm

SKU: 33819-1500
$13.95USD or lower Each
Quat Test Strips Very High Level 10000ppm

Quat Test Strips Very High Level 10000ppm

SKU: 33819-10K
$16.95USD or lower Each
Residual Quat 10-100 ppm

Residual Quat 10-100 ppm

SKU: 33819-100
$13.95USD or lower Each
More Information

Quaternary Ammonium Disinfection Compound Chemical Structures

Quaternary ammonium compounds are cationic surfactants (positively charged surface-active agents) that are more chemically complex than other disinfectants. Their name derives from the central nitrogen that is bound to four (quaternary) organic groups.

Click on any of the quats listed below to view the structural variability that contributes to their diverse biological & antibacterial activity. Differences in aromatic & alkyl side groups & aliphatic chain lengths effect bactericidal activity with otherwise antibiotic resistant bacteria.

Indigo&ref; QAC test strips are calibrated for Oasis 146 but can accurately test any single or multi-quat based disinfectant. Many vary only in the length of their alkyl chains. Chemistry, microbiology & pharmacology instructors & researchers may find our 3D Molecular Model Builder useful in comparing the following:
  1. benzalkonium chloride
  2. benzethonium chloride
  3. cetalkonium chloride
  4. cetylpyridinium chloride
  5. cetrimonium
  6. cetrimide
  7. diisobutylphenoxyethoxyethyl dimethyl benzyl ammonium chloride
  8. tetraethylammonium bromide
  9. didecyldimethylammonium chloride
  10. ipratropium bromide

Buying your quats in concentrated form is cheaper than pre-diluted. BUT, knowing how to dilute them may not be obvious. Read this section in our blog: How to Dilute Quats.

Advantages & Disadvantages


  • Nontoxic, odorless, colorless, noncorrosive, nonirritating
  • Relatively stable in the presence of organic matter
  • Active over a wide pH range but best in the range of pH 8-11


  • Slower at killing some microorganisms
  • Not compatible with some detergents
  • Not compatible with hard water
  • Color charts start to deviate at 45oC (110oF) & above

Additional material that may interest you:
  1. Quaternary Ammonium Compounds-Organic Disinfectants. What are quats, how do they work & how to dilute?
  2. Test Strip Expiration Dates; Good Today, Dead Tomorrow? Don't toss good test strips away. Good today doesn't mean bad tomorrow.
  3. Diluting Chlorine, Peroxide, Quats is Easy. Understanding metric makes it very easy to dilute disinfectant to any ppm from bottles to bucketfuls.
  4. Can 10ppm of Sulfite & Quat Really Mean Zero? Test strips can detect residual QACs down to 10ppm which is considered safe.

How Quat Test Strips Work

Quat test strips do not measure the concentration of dissolved quaternary ammonium compounds (QACs) directly. They actually use acidobasic indicators (normally used for pH determination), buffers, surfactants, and other ingredients to create a micro-environment on the test pad where the indicator dyes react to the presence of the quat and not to the pH of the test solution. It is as a consequence of the interaction between the molecules of the indicator dyes and quat that results in a different color of the test pad that we observe.

This is based on what is known as the "pH indicator error" (when the indicators change color without a change in solution pH) which relies on a carefully calculated amount of buffer on the test strip that excludes any contribution to pH other than the quat itself. It is this "error" that is utilized for the detection of compounds of interest (The QACs in this case). In other words, the assumption is the quat has been dissolved in tap water that might be slightly acidic, neutral or slightly alkaline. "Alkaline water" for example would have absolutely no effect. However, some quat formulations have additives such as tetrasodium EDTA which strongly shifts pH towards an alkaline level of 11-12 that completely throws off the test strip reading.

Overall, this is a reliable semi quantitative test method that is accurate typically to +/- 10% & suitable for confirming the correct dilution of quat concentrates in the "field". For more precise lab work, instruments such as GC/MS can deliver quantitative results on the order of several magnitudes greater & over a wider dynamic range.

Temperature and QAC Strips PPM Reading Relationship

(Results for Hyamine 1622 (Fluka) warmed up from 35oC to 60oC (95-140oF))

T (oC)  vs QAC strips readings at: 0; 50; 100; 200; 400 ppm

35oC: Readings ok for 0-400ppm
40oC: Readings ok for 0-400ppm
45oC: 0, 50, 100 ppm readings ok; 200 & 400 ppm read~ 1/2 color square higher
50oC: 50, 100 ppm read~ 1/2 color square higher; 200, 400 ppm read 1 color square higher
55oC: Readings 1 color square higher across whole range
60oC: Readings 1 color square higher across whole range



Follow the directions on the label. All our quat strips are "quick response". Dip the strip & compare to the color chart within 5-10 seconds. If you wait a minute as with other strips, the color will develop further & give a false high reading.

Some sources have raised concerns about the safety of quaternary ammonium compounds. Handling concentrated QACs may merit wearing PPC such as gloves, eye protection and even a respirator.

Frequently Asked Questions

FAQ for Quat Test Strips

Yes. These didecyl dimethyl ammonium chloride, alkyl(C12-C16) dimethyl benzyl ammonium chloride, octyl decyl dimethyl ammonium chloride, dioctyl dimethyl ammonium chloride and others have been shown to kill molds. Read more in our blog: Quaternary Ammonium Compounds-Organic Disinfectants. If you are interested in the chemical structures of these compounds, you can view them in our 3D Molecular Model Builder

Quats are cationic biocides (antimicrobial compounds) with net positive electrical charges that bind & disrupt negatively charged bacterial cell membranes causing their death.

Absolutely not! Mixing concentrated chlorine bleach & quaternary ammonia compounds can produce toxic vapors.

Chlorine bleach contains sodium hypochlorite, a powerful oxidizing agent that can corrode most metals & react to produce toxic chlorine gas. Its principle advantage is that it is cheap & readily available. Quats are cationic detergents that are relatively low in toxicity by comparison but its surfactant nature produces a residual film with broad spectrum germicidal characteristics.

According to the Household & Commercial Products Association (HCPA): "Quats are a well-understood and effective class of chemicals, usually classified by chemical identifiers ADBAC and DDAC. Numerous reputable studies show no sign of systemic toxicity in humans". 

On the other hand, some articles do question the safety of quats. Considering the importance of surfactants in lung alveoli, it may be prudent to handle concentrated quats only in well ventilated areas or wear a respirator and goggles during the dilution process.

Lysol disinfecting wipes are infused with 0.26% benzalkonium chloride [aka Alkyl (C14, C12, C16) Dimethyl Benzyl Ammonium Chloride]. This is very close to 2500ppm so the best quat strip to confirm they are fresh is our 0-10000ppm quaternary ammonium test strips. Simply pressing the test strip pad against a moist disinfecting wipe for a few seconds should be enough.

Alkyl dimethyl benzyl ammonium chlorides (BACs) are one type of QAC found in cleaning products & disinfectants in homes. If diluted correctly & used appropriately, they are considered safe.

Three Indigo® quat test strips are supplied in desiccant lined vials & 1 in a ziploc pouch. The latter is more economical for the most popular range, 0-400ppm, which is also least sensitive to environmental conditions. The lower & higher range QAC test strips are more sensitive & desiccant vials allow for a guaranteed 3 year shelf life as well.

Indigo® Quick Response QAC Test strips (Quaternary Ammonium Compounds) cover the range of 0-400ppm & give accurate readings after 1 second. The 1500 & 10000ppm do this in 5 seconds and the residual 100ppm in 10 seconds. All Indigo QAC test strips are designed to work for most single, dual and 4-chain quat disinfectants.

If an Indigo® Quick Response QAC strip indicates a ppm level well below government recommended levels for a given dilution, the solution should be replaced. If the color match is close but not quite there, try topping up with more concentrate & test again.