FEATURE QUAT’S IT ALL ABOUT?
The cleaning disinfectants that you use on a daily basis may not be doing the job properly, but why is this? It could be down to something known as ‘quat binding’. Robert Kravitz, our US correspondent for the cleaning industry, explains what this is, and how to avoid it.
Ten years ago, various studies started reporting that the disinfectants we are using to clean medical facilities, restrooms, schools, and other locations may be becoming less effective. For instance, one of the studies reported that: “If bacteria are exposed to biocides (disinfectants) repeatedly, for example during cleaning, they can build up resistance to disinfectants and antibiotics. Such bacteria have been shown to contribute to hospital- acquired infections.”*
The studies indicated that possible solutions to this problem will require the development of new types of disinfectants to address these disinfectant-resistant bacteria. In the meantime, cleaning professionals are advised to use disinfectants only where and when needed.
But what if they are using disinfectants ‘only when and where needed’ and still finding, using ATP testing procedures for instance, that germs and bacteria are present on surfaces after cleaning? In such cases, something else may be going on and it may be what we now refer to as ‘quat binding’.
Quaternary ammonium chlorides, otherwise known as ‘quats’, are the active ingredient in many disinfectants that kill germs and bacteria on surfaces. However, what has been discovered is that quats are ‘positively charged’ surfactants that are attracted to the fibres in many types of cloths, mops, and other tools used for cleaning.
This is because these fabrics are negatively charged. As the positively charged quats become absorbed into the negatively charged cleaning cloths and mops, they start to lose their effectiveness. Further, this is an ongoing process. For instance, the longer the cloth, is used, the more the quats are absorbed into it.
Just to show you how this happens and how much it impacts the
32 | Tomorrow’s Cleaning September 2016
pathogen killing power of the disinfectant, in one test a bucket is filled with one gallon of water diluted with a disinfectant at one half ounce per gallon. The quat level – indicating the effectiveness of the disinfectant – is measured at 800 parts per million (PPM). A cleaning cloth is then placed into the bucket and allowed to soak for ten minutes. After ten minutes, the quat level of the solution is now 400 PPM, indicating that half of the killing power of the disinfectant has been absorbed, cutting the killing power of the disinfectant in half.
POSSIBLE SOLUTIONS Now that we know what quat binding is and how it can impact the killing power of a disinfectant, what cleaning professionals need to know is how to address this challenge. The following are some of the options we have:
Always clean surfaces first and then disinfect. This is true whenever we use a disinfectant. According to the U.S. Environmental Protection Agency: “Germs can hide underneath dirt and other material on surfaces where they are not affected by the disinfectant. Dirt and organic material can also reduce the germ-killing ability of some disinfectants.” By cleaning first, we can help remove these hidden germs.
Spray surfaces directly and then wipe. This can be very effective if the cleaning cloth is changed frequently. When sprayed directly on the surface, the disinfectant has a greater chance to work without its effectiveness being hampered. However, be careful. Inhaling disinfectants can be harmful to the user. Additionally, this process often results in the overuse of disinfectants, and disinfectants tend to be costly cleaning solutions. Further, if not properly wiped clean, the chemical residue can attract new soils and contaminants to the surface.
Dip then wipe: Similar to spraying surfaces, this method of filling
a bucket with properly diluted disinfectant and then applying it to a surface can prove effective as long as the cleaning cloth used is not left in in the bucket too long and is changed frequently. However, over time, quat binding will still likely occur. (See: Why Frequent Cloth Changes Are Necessary)
Spray then vac: What is likely the most effective solution is to avoid using a cleaning cloth at all. This is possible using what ISSA calls a spray-and-vac (no-touch) cleaning system. Properly diluted disinfectant is sprayed on to surfaces; after proper dwell time, the same surfaces are pressure rinsed and then cleaning solution and contaminants are vacuumed up. This process essentially eliminates quat binding.
WHY FREQUENT CLOTH
CHANGES ARE NECESSARY Along with concerns about quat binding, we must be aware that the more soiled the cleaning cloth becomes, the less effective the disinfectant is at killing germs. Further, the soiled cleaning cloth can contaminate other surfaces because it is now spreading contaminants.
OTHER FACTORS
TO BE AWARE OF Cleaning professionals should also be aware of additional factors that can impact quat binding. For instance, it only takes about five minutes for the cleaning cloth to begin absorbing the disinfectant. This indicates just how fast quat binding can occur.
Other factors include:
• While microfibre cloths and mops have been proven to be more effective at removing contaminants, quat binding can and does occur with microfibre as well. This is especially true if the microfibre soaks in the disinfectant cleaning solution.
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