NaDCC – HOCI Hypochlorous Acid
Question & Answer series with chemist and environmental microbiology scientist, Mark Hodgson, LRSC, CMIP of Kersia Medical.
Hodgson is an authority on disinfectant chemistries, whose articles have been published extensively in infection prevention journals. He explains the technology behind the singular NaDCC chemistry in EvaClean PurTabs and PurOne.
EC: What is NaDCC and why is this chemistry a better disinfectant?
MH: NaDCC is an organic chlorine release agent that produces hypochlorous acid (HOCl) when dissolved in water, which creates a highly effective disinfectant. HOCl is the same molecule that is naturally produced in macrophages to kill ingested bacteria in our bodies.
Depending on the pH of the water, HOCI dissociates into hydrogen ion and hypochlorous ion (OCI-) when dissolved. Though OCI- demonstrates biocidal activity, it is 4 to 10 times less effective than HOCI. The higher the pH, the greater the dissociation and the lower the efficacy. For example, the most common chlorine donor is BLEACH and, though it also produces HOCI, the solution is highly alkaline with a pH of 12 to 13. Hence, over 90% of the HOCL present is the lesser effective OCI-.
Because the NaDCC chlorine donor is an organic molecule, the HOCl produced is a neutral pH. Therefore, the majority of it remains the more effective HOCl. From the perspective of the end-user, this means NaDCC can produce effective disinfection at lower concentrations than bleach. Moreover, as a pH-neutral solution, it also presents fewer health risks.
EC: What do the terms “slow release” and “CAD” mean?
MH: NaDCC has two molecules of chlorine attached to the organic donor. The first is released as soon as NaDCC dissolves in water to produce HOCl, while the second remains attached to the organic donor. As the HOCl does its job killing pathogens, “slow release” occurs when the first chlorine molecule is consumed and the second is released. Thus, the ratio of the chlorine released to chlorine in reserve is always 50:50. This is a major advantage in areas with high organic loading such as biofilms, because the chemistry continues to be effective even when there is a high chlorine demand.
As the disinfectant dries on a surface, the HOCl will evaporate, while any chlorine still bound to the organic donor remains on the surface. If surfaces are wetted again by contact with aerosol droplets containing pathogens, the disinfectant provides persistent action when the donor releases its remaining HOCl molecule. Research has shown this persistent action can last up to 24 hours if the surface is undisturbed, and one study proved HOCl continued to kill C. diff even after 24 hours. That’s why HOCl is a true continuously active disinfectant (CAD).
