LAR Process Analysers QuickTOC purity - Operating Principle of the Analyser; Measurement of TOC; The Sum Parameter TOC; High Temperature Method at 1,200°C

04E3920 User Manual QuickTOC
®
purity
ATEX 2 13
LAR | PROCESS ANALYSERS AG
2 Operating Principle of the Analyser
2.1 Measurement of TOC
2 Operating Principle of the Analyser
The online measurement system determines the corresponding parameters using the high temperature
method at 1,200°C according to the following measurement methods:
:
• TOC-Difference Method: TC, TIC, TOC (in accordance with DIN EN 1484:1997 and US-EPA 415.2)
• TOC-Direct Method: NPOC (in accordance with DIN EN 1484:1997 and US-EPA 415.2)
• TConly Method: TC (in accordance with DIN EN 1484:1997 and US-EPA 415.2)
2.1 Measurement of TOC
2.1.1 The Sum Parameter TOC
The TOC (Total Organic Carbon), in addition to COD (chemical oxygen demand) and BOD (biochemical
oxygen demand), is an important sum parameter for assessing the organic load of water. Because all
organic carbon compounds are read and specified as mass carbon (unit: mg/l C), the TOC is a precisely
definable, absolute parameter, and can be directly measured. Other parameters are always stated in
relation to the TOC. Their interrelations and respective meanings are shown below:
The basis of all TOC measurement methods is oxidation - normally using thermal or wet chemical oxi-
dation of organically-ligated carbon to carbon dioxide (CO
2
). The CO
2
produced is detected and deter-
mined quantitatively.
2.1.2 High Temperature Method at 1,200°C
In the ceramic furnace without catalyst the carbon compounds are reliably oxydized at a combustion
temperature of 1,200°C. This high temperature method does not require a filtration. The NDIR detector
(Non-Dispersive Infrared) detects the CO
2
contents of the sample. If required, the samples can be ho-
mogenised and be measured with all particles contained within, allowing for measurement of the TRUE
TOC.
2.1.3 High Temperature Method vs. Wet Chemical Method
High temperature methods (as well as wet chemical methods, such as the UV persulphate method) are
used to determine the TOC. The advantages of the high temperature method compared to the wet che-
mical UV persulphate method is described in the European Norm EN 1484:1997:
“Devices which determine the TOC with the UV persulphate method are not appropriate for media con-
taining suspended and turbided solids”.