Application
Note: 42021
Total Organic Carbon in water with high
salt matrix using the HiperTOC analyzer
Introduction ASTM D 4779: Total, Organic and Inorganic Carbon in
Key Words Nowadays, wastewater treatment facilities are monitored High Purity Water by UV persulfate
on efficiency. The Total Organic Carbon content (TOC Oxidation and/or Infrared Detection TC,
• High Salt Matrix
value) can be used for this purpose. High TOC values IC, TOC in production water, high
• NPOC after the waste water treatment plant indicate significant purity process water
concentrations of organic materials, disinfectants and
• TOC
disinfectant side-products, and insufficient performance of Principle of operation
• Total Organic the wastewater treatment facility, where on the other hand The integrated XYZ auto sampler of the HiPerTOC
Carbon the influent needs to be controlled to avoid the abundance analyzer introduces the sample automatically into the
of bacterial cleaning. reactor. Inside the reactor, the UV-light and the persulfate
There are different techniques to measure the TOC, ensures a complete oxidation of the water sample and all
the most common are the High Temperature and the UV organic carbon is being oxidized to CO2. The CO2 gas is
Persulfate method. High salts concentrations may have "air dried" by a Peltier cooler. The CO2, together with the
impact on the efficiency of the catalyst if the technique is carrier gas, is led through two IR detectors, one being 10
performed at 680 °C. Normally inorganic chloride inhibits times more sensitive than the other one. To better fit the
the oxidation reaction of persulfate, according the reaction: analytical range, both can be calibrated simultaneously,
resulting in less need for dilution and always-accurate
_ _ _ results, without over-ranging. ThEuS analytical software
2 UV 2
2X S2O 8 X2 2SO 4 supports storage and uses several multiple point
calibration lines. Working ranges used are standard or
TOC analysis can also suffer from interferences and customers defined. Generated data and peaks can be
corrosive effects normally associated with high salt samples. recalculated afterwards, or during analysis. The TOC is
The HiPerTOC analyzer is designed to be resistant to calculated according to the NPOC (Non-Purgable Organic
these effects: Any potential interfering component is Carbon) method.
removed and the detectors are not harmed by the
corrosive effect. Samples preparation
The special design of the reactor of the HiPerTOC To investigate the destruction robustness and the high salt
makes TOC analysis using UV-persulfate oxidation method matrix resistance of the HiPerTOC, three artificial samples
possible. This report demonstrates the robustness of the are prepared. Each sample contains a specific concentration
UV-persulfate method for samples with high salt matrix. of organic carbon, respectively approximately 20, 50 and
100 mg/l. Each sample then is divided in two separate
Referenced Documents sample vials; to one sodium chloride is added to a
The HiPerTOC analyzer complies with the following concentration of 2.5%, the other part is unchanged.
standard methods: This results in a set of 6 samples (see table below). It is to
EN 1484: Water analysis: Guidelines for the be expected that the TOC values of the high salt matrix
determination of Total Organic Carbon matches its clean matrix equivalent.
(TOC) and Dissolved Organic Carbon
(DOC) SAMPLE MATRIX TOC
ASTM D 4839: Total Carbon and Organic Carbon in A High salt 20
Water by UV-persulfate Oxidation, B High salt 50
and/or Infrared Detection TC, IC, TOC C High salt 100
in water, waste water and sea water D Clean 20
E Clean 50
F Clean 100
System settings In addition to these
UV Reactor: Heated to approximately 85°C offices, Thermo Electron
Carrier gas: Oxygen, 250 mL/min Corporation maintains
Sample volume: 1000 µL a network of represen-
Injection speed: 25 µL/s tative organizations
Sampler: XYZ-sampler throughout the world.
Calibration
A calibration stock solution is prepared by dissolving 2.125g
anhydrous potassium hydroxyl phthalate (KHC8H404) in
1 liter of ultra pure water, giving 1 g organic carbon per
Australia
liter (1000 mg/L). From this solution six calibration +61 2 9898 1244
standards are prepared by dilution giving 2, 5, 10, 20, 50 Austria
and 100 mg carbon per liter. These calibration standards Figure 1. Integration of sample C +43 1 333 50340
are used to calibrate the HiPerTOC analyzer. Belgium
+32 2 482 30 30
Canada
+1 800 532 4752
China
+86 10 5850 3588
France
+33 1 60 92 48 00
Germany
+49 6103 4080
Italy
+39 02 950 591
Japan
+81 45 453 9100
Netherlands
+31 76 587 98 88
Nordic
Figure 2. Integration of sample F +46 8 556 468 00
South Africa
+27 11 570 1840
Discussions Spain
Graph 1. Calibration line The calibration line of the analyzer is linear up to 100 mg +34 91 657 4930
per liter (graph 1). The relative standard deviations of all Switzerland
STANDARD (mg C/L) AREA (mV/sec) samples are less than 1 %, based on 5 replicates. In the +41 21 694 71 11
Blanc 84.8 table below the samples with the same organic carbon UK
+44 1442 233555
2 192.8 concentration are compared and with different matrices.
USA
5 338.6 +1 800 532 4752
SAMPLE MEAN SAMPLE MEAN DEVIATION DEVIATION
10 588.8
(mg C/L) (mg C/L) (%)
20 1064.7 www.thermo.com
A 21.7 D 21.1 0.6 2,8%
50 2462.0
B 51.0 E 50.3 0.7 1,4%
100 4738.4
C 98.9 F 98.6 0.3 0,3%
Results The signal of the samples with a high salt matrix show Thermo Electron
Corporation, Delft,
some tailing (figure 1) compared to the signal of samples the Netherlands is
SAMPLE MEAN (mg C/L) RSD* (%)
without a high salt matrix (figure 2). Despite of this ISO certified
A 21.7 0.93
phenomenon, the recovery of the TOC value of the ©2004 Thermo Electron
B 51.0 0.73 Corporation. All rights
sample with a high salt matrix is excellent. reserved. All trademarks are
C 98.9 0.34 the property of Thermo
D 21.1 0.73 Electron Corporation and
Conclusions its subsidiaries.
E 50.3 0.55
The TOC values of the samples are all as expected. Specifications, terms and
F 98.6 0.86 pricing are subject to
The UV/persulfate NPOC method demonstrates complete change. Not all products are
available in all countries.
* n=5 oxidative power in difficult salt matrices. The HiPerTOC Please consult your local
did not suffer from any interferences or corrosive effects. sales representative for
details.
AN42021_E 10/04
