04E3920 User Manual QuickTOC
®
purity
ATEX 2 81
6 Reagents and Calibration Standards
6.1 Reagents
LAR | PROCESS ANALYSERS AG
6.1.5 Other Chemicals
If ambient air is cleaned with LAR equipment as a carrier gas, the following chemicals are required:
• Activated carbon (1) (instrument air / zero air generator supply only)
• Highly volatile organic compounds (such as solvents) in the ambient air may adversely affect the
accuracy of the measurement, depending on the installation site. All volatile carbons (VOCs) must be
removed from the ambient air. Activated carbon is used for this task.
• Soda lime pellets (2)
• The CO2 in the ambient air is removed by pellets.
Saturation of the chemicals
When the chemicals are saturated with volatile carbon (VOC), the analyser's base signal rises. The si-
gnal value depends on the detector connected to the analyser.
If the activated carbon has changed color, the activated carbon must be replaced. See chapter 9.3.5.1
from page 169 onwards
If the soda lime cookies have changed color, the soda lime cookies must be replaced. See chapter
9.3.5.1 from page 169 onwards.
Production of calibration standards (CODo method)
The concentration of the standard depends on the set measuring range. It should be at least 50% and
max. 100% of the full scale value. The standard is set according to DIN EN 1484: 1997.
Example:
If a measuring range of up to 1,000 mg / l COD is set, the calibration standard must be between
500 mg / l and 1,000 mg / l COD.
Ideal concentration: 750 mg / l or 800 mg / l COD.
6.1.6 Calibration Standards - TOC-Difference Method
This section explains how you can prepare the calibration standards for the TOC-Difference Method.
First, a stock solution needs to be prepared which can then be diluted to obtain the required calibration
standard concentration.
Danger
Danger of chemical burns
The soda cookies are corrosive.
Use gloves, goggles and dust mask.
When handling the soda lime cookies, follow the safety guidelines for handling corro-
sive chemicals.
Notice
To minimise mistakes, LAR always recommends using the stock solution as the initial
solution for dilutions.
The stock solution and its diluitions can be used as a calibration standard.
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