IKA AOD 1 - Manual (Page 60)

IKA  -WERKE AOD 1 Ver. 01 01.03
Page 6-7
To vent a decomposition vessel using the Venting Station C 7030, please follow
the operating instructions for the Venting Station C 7030.
Slow venting through a washing bottle is, for example, essential for iodine determi-
nation.
Checking for complete combustion
Open the decomposition vessel and check the crucible and decomposition vessel
wall for signs of incomplete combustion. If you find evidence of incomplete combus-
tion, reject the results of that test, and repeat it.
Incomplete combustion can be caused if the oxygen pressure in the decomposition
vessel is too low, or it indicates that a combustion aid is required.
Preparation for analysis
Transfer the absorption solution carefully to a measuring flask with distilled water. All
components of the decomposition vessel must be thoroughly rinsed. For analysis
with ion chromatography, it is recommended that dissolved carbon dioxide is re-
moved from the absorption solution.
Alternatively, a quick but less accurate determination can be carried out by filling a
decomposition vessel with a measured quantity of distilled water to obtain a "defined
volume" (e.g. 20 ml or 100 ml). This can then be subjected to gravimetric or volu-
metric analysis.
After the distilled water has been added, the vessel must be closed again, and, with
the aid of the Oxygen Filling Station C 48, filled with oxygen to about 3 bar. This is
necessary to close the valve on the vessel.
The vessel must then be vigorously shaken. A homogeneous distribution of the sub-
stance to be analysed and the condensate in the liquid phase is a prerequisite for
the subsequent analysis.
After venting again, the ions and elements of interest can be determined using a
suitable method of analysis.
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Analysis
The detection method for dissolved ions can be selected by the user. Ion chroma-
tography, detection with ion-selective electrodes, or titration are suggested methods.
Particularly when the samples being tested contain other halogens (iodine, fluorine
or bromine) besides chlorine and sulphur, and very consistent detection is required,
ion chromatography is to be preferred. For further information, please refer, for ex-
ample, to DIN 38414 Part 18, Determination of AOX in sludges and sediments“.
IKA
 can provide further information about Hg and As determination using AAS
spectroscopy.
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