Sample Flow Path - GE Sievers 900 Series Operation And Maintenance Manual

Sample Flow Path

Discrete samples can be measured by the Sievers 900 On-Line TOC Analyzer by inserting a filled 40
mL sample vial into the IOS System. Continuous monitoring is accomplished by plumbing a sample
line to the inlet of the IOS System.
After sample is introduced into the Analyzer, 6M phosphoric acid (H
user interface) is injected into the sample at the programmed flow rate to reduce sample pH to 2;
this allows for accurate measurement of TOC and IC.
If the optional Inorganic Carbon Remover (ICR) unit is utilized, additional acid is added to the sample
to remove excess IC by the ICR. In the ICR, IC is removed by vacuum degasification.
The acidified sample is then combined with 15% ammonium persulfate ((NH
Oxidizer in the user interface) to promote oxidation of the organics. The sample travels through a
mixing coil and on to a stream splitter.
The stream splitter divides the sample stream into two equal but separate flows. One stream is
processed for the measurement of IC; the other is processed for measurement of TC.
The TC stream passes to an oxidation reactor where the sample is exposed to UV light. The
combination of UV light and, depending on the application, persulfate oxidizes the organic
compounds in the sample, converting carbon to CO
around the UV lamp. The UV lamp emits light at 185 and 254 nm resulting in the formation of
powerful chemical oxidizing agents in the form of hydroxyl radicals produced by the photolysis of
water (eq. 1) and persulfate (eq. 2, 3):
The hydroxyl radicals (OH·) will completely oxidize organic compounds, converting the carbon
atoms of the organic compound into CO
GE Analytical Instruments ©2009
. The reactor is a spiral quartz tube wrapped
2
H O + hν (185 nm)
2
-2
S O + hν (254 nm)
2 8
-
SO · + H O HSO
4 2 4
.
2
Organic Compounds + OH·
55 of 236
PO ) (referred to as Acid in the
3 4
) S O
4 2 2
OH· + H· (1)
-
2 SO · (2)
4
-
+ OH· (3)
CO + H O(4)
2 2
) (referred to as
8
DLM 90488-01 Rev. A