●Water solubility in all proportions
●Acceptability of odor or no odor
●Stability in concentrated and use dilu-
tion
●Ease of use
●Ready availability
●Inexpensive
●Ease of measurement in use solutionA standard chemical sanitizer cannot be
effectively utilized for all sanitizing require-
ments. The chemical selected as a sanitizer
should pass the Chambers test (also referred
to as the sanitizer efficiency test): Sanitizers
should produce 99.999% kill of 75 million to
125 million Escherichia coliandStaphylococ-
cus aureuswithin 30 seconds after applica-
tion at 20°C. The pH at which the compound
is applied can influence the effectiveness of
the sanitizer. Chemical sanitizers are nor-
mally divided according to the agent that
kills the microorganisms.
Chlorine Compounds
Liquid chlorine, hypochlorites, inorganic
and organic chloramines, and chlorine diox-
ide function as sanitizers. Their antimicrobial
activity varies. Chlorine gas may be injected
slowly into water to form the antimicrobial
form, hypochlorous acid (HOCl). Liquid
chlorine is a solution of sodium hypochlorite
(NaOCl) in water. Hypochlorous acid is 80
times more effective as a sanitizing agent
than an equivalent concentration of the
hypochlorite ion. The amount of HOCl is
dependent on a pH of the solution. A lower
pH enhances HOCl formation but stability
decreases. However, as the pH decreases
below 4.0, increasing amounts of toxic and
corrosive chlorine gas are formed. Chlorine
is more stable at a high pH, but is less effec-
tive (Anon., 2003). The activity of chlorine
as an antimicrobial agent has not been fully
determined. Hypochlorous acid, the most
active of the chlorine compounds, appears to
kill the microbial cell through inhibiting glu-
cose oxidation by chlorine-oxidizing sulfhydryl
groups of certain enzymes important in car-
bohydrate metabolism. Aldolase was consid-
ered to be the main site of action, owing to
its essential nature in metabolism.
Other modes of chlorine action that have
been proposed are: (1) disruption of protein
synthesis; (2) oxidative decarboxylation of
amino acids to nitrites and aldehydes;
(3) reactions with nucleic acids, purines,
and pyrimidines; (4) unbalanced metabo-
lism after the destruction of key enzymes;
(5) induction of deoxyribonucleic acid
(DNA) lesions with the accompanying loss
of DNA-transforming ability; (6) inhibition
of oxygen uptake and oxidative phosphory-
lation, coupled with leakage of some macro-
molecules; (7) formation of toxic N-chlor
derivatives of cytosine; and (8) creation of
chromosomal aberrations.
Vegetative cells take up free chlorine but
not combined chlorine. Formation of chlo-
ramines in the cell protoplasm does not
cause initial destruction. Use of^32 P in the
presence of chlorine has suggested that there
is a destructive permeability change in the
microbial cell membrane. Chlorine impairs
cell membrane function, especially transport
of extracellular nutrients. Chlorine-releasing
compounds are known to stimulate spore
germination and subsequently to inactivate
the germinated spore.
Granular chlorine sanitizers are based on
the salts of an organic carrier that contains
releasable ions. Chlorinated isocyanurate is a
highly stable, rapidly dissolving chlorine car-
rier that releases one of its two chloride ions
to form NaOCl in aqueous solution. Buffer-
ing agents, which are mixed with the dry
chlorine carrier in these products, control the
rate of antimicrobial activity, corrosion
characteristics, and stability of solutions of
the sanitizers by adjusting the solution to an
optimal use pH.