Endress+Hauser Analytik Jena Multi X 2500, Руководство по эксплуатации

Страница: 16 / 124

Function and layout of the multi X 2500 multi X 2500
16
There is the option to use the multi X 2500 for determining the TOC in aqueous
samples. For this purpose, the analyzer must be upgraded with the TOC module.
System setup and execution of the TOC measurement are described in the separate
user manual of the TOC module.
3.2 Measuring methods
3.2.1 General information
The methods for AOX, EOX and POX determination are specified in various different
international standards and regulations (e.g. ISO 9562). All instructions and
definitions contained in these documents with regard to sampling, sample preparation
and execution of the analysis must be observed.
3.2.2 AOX determination
The parameter AOX describes the sum of adsorbable organically bound halogens
(chlorine, bromine, iodine). The halogens are adsorbed onto activated carbon under
defined conditions (pH < 2 with HNO
3
) from a water sample or a solid sample (sludge
and sediments). The loaded activated carbon is then combusted in the oxygen stream.
In the chlorine module, the hydrogen halides which are produced are absorbed in the
electrolyte solution. The halide ions are determined argentometrically.
Two possible methods for absorbing the activated carbon are:

Column method

Batch method
Another possible method is the stirring method (or carbodisc method) which is not
described in further detail in this manual.
The prepared water sample is passed through columns packed with activated carbon.
During this process, the organically bound halogens are adsorbed onto the activated
carbon. Inorganic halides are washed out using a nitrate solution.
The samples for the column method can be prepared with the automatic sample
preparation modules APU 28, APU 28 S, APU 28 SPE and their flexi versions, APU sim
or AFU 3 (with the column method kit).
Activated carbon and nitrate solution are added to the prepared sample in an
Erlenmeyer flask. The mixture is then shaken for one hour. The suspension is then
passed through a filtering system. The filter cake is washed with nitrate solution.
The sample for the batch method can be prepared using the automatic filtration unit
AFU 3.
TOC determination
Column method
Batch method