multi N/C 2100S (duo, pharma)
Function and design
29
The CO
2
or NO concentration is detected several times every second. An integral over
time is calculated from this signal sequence. The integral is proportional to the concen-
tration of the carbon or nitrogen in the measurement solution. Afterwards, the calcula-
tion of the carbon or nitrogen content in the sample is performed via a previously deter-
mined calibration function.
3.4
Measuring methods
The detection of several parameters can be combined in the multiWin control and anal-
ysis software.
3.4.1
TC analysis
TC: Total Carbon
In TC analysis, the total carbon contained in the sample, i.e. the organic and inorganic
bound carbon, as well as elemental carbon, is detected.
The sample is dosed automatically into the combustion tube and digested, and the gen-
erated carbon dioxide is detected.
TN
b
detection is possible in parallel to TC detection.
3.4.2
TOC analysis
TOC: Total Organic Carbon
In TOC analysis, the total organic bound carbon contained in the sample is detected.
TOC determination is carried out in the analyzer using the differential method which can
be described with the following formula.
TOC = TC – TIC
TOC - total organic carbon
TC - total carbon
TIC - total inorganic carbon
Two sequential measurements are used on one sample to determine TIC and TC. The
calculated difference is given as TOC. The differential method detects volatile as well as
non-volatile organic carbon compounds.
TOC analysis can be used when the sample contains easily purgeable organic substances
such as benzol, cyclohexane, chloroform, etc. If the TIC content of the sample is signifi-
cantly above the TOC content, TOC analysis should not be applied.
TN
b
detection is possible in parallel to TOC detection.
3.4.3
TIC analysis
TIC: Total Inorganic Carbon
In TIC analysis, the total inorganic carbon from carbonates and hydrocarbonates, as well
as dissolved CO
2
, is detected.
Cyanides, cyanates, isocyanates and carbon particles are not detected.
An aliquot of the sample is dosed directly into the TIC reactor to determine the inorganic
carbon (TIC). The CO
2
is purged and detected.
