Benzalkonium chloride (BAC) is a mixture of quaternary ammonium compounds that is commonly used as a biocide and disinfectant. It is effective against bacteria, viruses, fungi and protozoa through disrupting the lipid bilayers of cellular membranes. BAC solutions work best at higher temperatures and prolonged exposure times. Newer BAC formulations combined with other quats have improved virucidal activity and efficacy. BAC is widely used in hospitals as a disinfectant due to its safety, though excessive amounts can harm marine life.

1. Benzalkonium Chloride (BAC) (ADBAC) Benzalkonium chloride solutions are rapidly
acting biocidal agents with a moderately long
Benzalkonium chloride, also known as alkyl duration of action. They are active against
dimethyl benzyl ammonium chloride and bacteria and some viruses, fungi, and
ADBAC, is a mixture of protozoa. Bacterial spores are considered to
alkylbenzyldimethylammonium chlorides of be resistant. Solutions are bacteriostatic or
various even-numbered alkyl chain lengths. bactericidal according to their concentration.
This product is a nitrogenous cationic surface- Gram-positive bacteria are generally more
acting agent belonging to the quaternary susceptible than Gram-negative. Activity is not
ammonium group. greatly affected by pH, but increases
substantially at higher temperatures and
ADBAC chemical case is comprised of 24 prolonged exposure times.
compounds that are structurally similar
Newer formulations using benzalkonium
quaternary ammonium compounds (quats) that
blended with various quaternary ammonium
are characterized by having a positively derivatives can be used to extend the biocidal
charged nitrogen covalently bonded to three spectrum and enhance the efficacy of
alkyl group substituents and a benzyl benzalkonium based disinfection products.
substituent. In finished form, these quats are This technique has been used to improve
salts with the positively charged nitrogen virucidal activity of quaternary ammonium-
(cation) balanced by a negatively charged based formulations to healthcare infection
hazards such as hepatitis, HIV, etc.
molecule (anion). The most common anion for Quaternary ammonium formulations are now
the quats in this cluster is chloride. However, the disinfectants of choice for hospitals. This is
other anions, such as saccharine and bromide on account of user and patient safety even on
are also used. contact with treated surfaces and the absence
of harmful fumes. Benzalkonium solutions for
It has three main categories of use; as a hospital use tend to be neutral to alkaline, non-
biocide, a cationic surfactant and phase corrosive on metal surfaces, non-staining and
transfer agent in the chemical industry. safe to use on all washable surfaces.
The use of appropriate supporting excipients
can also greatly improve efficacy and
detergency, and prevent deactivation under
use conditions. Formulation requires great care
as benzalkonium solutions can be readily
inactivated in the presence of organic and
inorganic contamination. Solutions are
incompatible with soaps, and must not be
The greatest biocidal activity is associated with mixed with anionic surfactants. Hard water
the C12-C14 alkyl derivatives. The mechanism salts can also reduce biocidal activity. As with
of bactericidal/microbicidal action is thought to any disinfectant, it is recommended that
be due to disruption of intermolecular surfaces are free from visible dirt and
interactions. This can cause dissociation of interfering materials for maximal disinfection
cellular membrane lipid bilayers, which performance by quaternary ammonium
compromises cellular permeability controls and products.
induces leakage of cellular contents. Other
biomolecular complexes within the bacterial Although hazardous levels are not likely to be
cell can also undergo dissociation. Enzymes, reached under normal use conditions,
which finely control a wide range of respiratory benzalkonium and other detergents can pose a
and metabolic cellular activities, are particularly hazard to marine organisms. Quaternary
susceptible to deactivation. Critical ammonium disinfectants are effective at very
intermolecular interactions and tertiary low ppm levels, so excess use should be
structures in such highly specific biochemical avoided.
systems can be readily disrupted by cationic
surfactants.
Compiled by Deniz Kaya -1-