Page 4 - Application Handbook - TOC

Sum parameter – Total Organic Carbon
TOC –Determination in drinking water
No. SCA-130-101
Drinking water is one of the main important
and life-sustaining food stuffs and is essential
to the survival of all known organism. It is a
crucial component for metabolic processes
and serves as solvent for many bodily
solutes. Water for human consumption must
be free from pathogens, pleasant to drink and
pure. Continuous monitoring is carried out
according to European Drinking Water
Regulation to ensure the greatest possible
security
■ European Drinking Water Directive
The Directive is intended to protect human
health by laying down healthiness and purity
requirements which must be met by drinking
water within the European Union (EU).
The directive applies to all water intended for
human consumption apart from natural
mineral waters and water which are medicinal
products.
The European drinking water directive
includes the category of indicator parameter
value specifications. These are not directly
linked to health problems but have an
indicator function.
This list of indicator parameters also includes
the TOC value (total organic carbon), which
has not been assigned a limiting value or
criterion but can be considered as a
cautionary warning for action under unusual
circumstances. Another indicator parameter
included in the list is oxidizability. This is a
measure for the sum of all chemically
oxidizable organically bound compounds
present in water.
With reference to drinking water limiting
values, this parameter is no cause for direct
health concern but can lead to regermination
or undesirable disinfection byproducts.
Oxidizability is proportional to the sum of
organically bound carbons that are
determined as DOC (dissolved organic
carbon) or TOC. Oxidizability can therefore
be replaced by the TOC parameter. The
frequency of determination of the parameter
indicators depends on the volume of water
that is produced or released in a water supply
area.
■ TOC determination in drinking water
When examining carbon compounds in
drinking water, it is apparent that the amount
of inorganic carbons, such as carbonates and
hydrogen carbonates, is much higher than
the organic fraction.