Metrohm 909 UV Digester User Manual
Page 35
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5 Carrying out sample digestion
909 UV Digester
￭￭￭￭￭￭￭￭
27
Note
Use the provided sample vessels
Only use the sample vessels made of quartz glass (6.2414.000)
that have been provided. Normal reagent glasses do not let UV
radiation through and do not ensure complete digestion. Clean
the sample glasses before use as described in Chapter 7.2.3, page
36.
2 Add nitric acid (w(HNO
3
) = 65%, for trace analysis) and hydrogen
peroxide (w(H
2
O
2
) = 30%, for trace analysis).
Samples with a low organic load are offset with the following
reagent concentrations:
￭
0.01 mL HNO
3
(w(HNO
3
) = 65%, for trace analysis)
￭
0.05 mL H
2
O
2
(w(H
2
O
2
) = 30%, for trace analysis)
The sample volume, the volume of the reagents and the digestion
parameters must be adjusted accordingly for samples with increased
organic load.
3 Place the PTFE stopper (6.1446.100) on the sample vessels. Leave the
sample vessel at Position 6 free for measuring the temperature.
4 Insert the sample holder into the wet end (see Chapter 3.5, page
17).
Note
Fully filled sample holder
Only a fully filled sample holder enables even temperature distribu-
tion to the samples. If you use fewer than twelve samples, fill the
remaining sample vessels with distilled water.
5 Insert the temperature sensor (6.1110.010) with attached thermom-
eter plug (6.1446.190) and spacer into the sample vessel at Position
6 and press it down.