Figure 2: Schematic diagram of UV persulphate decomposition.
Figure 1: Schematic diagram of thermal decomposition.
standards of the inorganic load of the water (conductivity),
the organic load can be verified by a sum parameter. With
these changes by the controlling authorities, the pharmaceutical industry can now monitor the organic load of ultra-pure water continuously and promptly. The manufacturers
of monitoring instruments already have experience with this
parameter from other pure and ultra-pure water producing
industries (e.g., semi-conductor industries).
The manufacturers have developed various techniques to
oxidize the organic carbon and the resulting carbon dioxide
can be measured. SWAN Analytic Instruments AG employs
the direct UV-oxidation method.
This report gives a brief outline of the general measuring
methods. Further, it illustrates the possibilities and limitations of the direct UV-Oxidation, as well as which technical
modifications were made to the monitoring instrument, AMI
Line-TOC, to improve the performance of the UV-reactor
and, therefore, the precision of the instrument.
Today, these are the main methods of TOC determination:
• Thermal decomposition with NDIR detection
• UV-Persulphate decomposition with NDIR detection
• UV-Persulphate decomposition with conductivity detection
• Direct UV-Oxidation with conductivity detection
Each process is based on the oxidation of the organic
carbon that is present in the water and the subsequent
measurement of the carbon dioxide which results from the
In the pharmaceutical industry the quality guidelines for the production of applied water are set at a partic- ularly high level. In order to guarantee the quality of the ultra-pure water at all times, more and more pharmaceutical producers employ an automatic and continuous
monitoring of processing plants and of ultra-pure water
cycles. The introduction of the TOC-content as a specification for ultra-pure water in the US pharmacopeia in 1998
was an important step for this development. Similar to the
■ By Roger Schmid, Industry Application Manager for UPW and Pharmaceutical Product Lines, Swan
Automated and continuous monitoring of ultra-pure water cycles
■ 20 NOV/DEC 2013 | PHARMACEUTICAL PROCESSING
■ PHARMPRO. COM
New Paths in TOC
Figure 3: Schematic diagram of direct UV oxidation.