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Sum parameter – Total Organic Carbon
TOC determination in particle-containing
samples - Cellulose test according to EN 1484
SCA-130-106
Depending on their origin, different effluents According to DIN 1484, the suitability of a
can contain substantial amounts of insoluble TOC measurement system for the analysis of
solids. These include clearly visible wastewater samples that contain solid matter
components that, in some cases, sediment must be tested. This is carried out using the
very quickly. This applies particularly to heavy so-called cellulose test (Appendix C of the
particles such as sand grains. Suspended above-mentioned standard).
solids such as fibers or flakes are naturally
less likely to sediment. However, they also ■ Cellulose test according to DIN EN 1484
cause a certain inhomogeneity of the sample The cellulose test is based on an aqueous
matrix. cellulose suspension with a carbon content of
100 mg/L. This corresponds to 225 mg
cellulose. The particle size ranges from 20
µm to 100 µm. Homogenization may only be
carried out under stirring. Alternative methods
such as ultrasound can break up the particles
and thereby provide erroneous results. Large
particles in particular have a tendency
tosediment rapidly.
Stirring speed is critical for this reason. Very
slow stirring leads to increased particle
sedimentation. Extremely high stirring speeds
lead to inhomogeneous particle distribution
due to centrifugal force. DIN 38402 part 30,
dealing with sample homogenization, serves
in this context as an excellent reference. A
solution should be stirred in such a way that
the vortex will amount to 10% of the filling
A variant of TOC determination is the level.
detection of DOC, Dissolved Organic Carbon.
The wastewater sample is filtered through a For three consecutive injections, the mean
membrane filter with a 0.45 µm pore size and value must lie within the range of 90 mg C/L
subsequently measured. In contrast to DOC, to 110 mg C/L (corresponding to a recovery
TOC (Total Organic Carbon) determinations of 90 – 110 %). The relative standard
must detect the total organic carbon in a deviation (RSD) may not exceed 10 %.
sample, including the insoluble components.
