Measuring method
multi EA 4000 Version 01.16 47
5.5.4 Other calculations
For all measurements where multiple determinations are carried out the average value (AV),
standard deviation (SD) and variation coefficient (VC) are calculated and displayed. For each
sample a triple determination can be carried out as a maximum.
When measuring TOC with the automatic TIC solids module in the differential method or
detecting the carbon after pyrolysis (TC-EC), only a single determination is carried out.
Average value
The average value of the final result is calculated from the concentrations determined for the
individual detections.
Boat blank value
The boat blank value is determined by introducing an empty boat or a boat with additives for
the sample into the combustion furnace and analyzing it.
The boat blank value can be determined separately and entered in the control and analysis
software multiWin. This value can change over time and must be redetermined before the
start of each measuring series. Otherwise the value last entered will be used.
5.6 Cl detection
The samples to be examined enter the combustion chamber in a quartz glass boat via an
open gas airlock. The sample is first pyrolized in the inert gas flow (argon). The resulting
pyrolysis products are fully incinerated in the oxygen flow after some delay.
The reaction completes in accordance with the following equation:
R-Cl
HCl + CO
2
+ H
2
O + oxides (8)
The share of HCl is determined coulometric after drying the measuring gas. The chloride
ions then react completely with the electrolytically generated silver ions to form silver chlo-
ride.
Ag
Ag
+
+ e
-
(9)
Ag
+
+ Cl
-
AgCl (10)
From the charge volume used up for generating the silver ions the chloride volume can be
calculated using Faraday's law.
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