Thermo Scientific Orion AquaMate UV-Vis, Руководство пользователя

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Chapter 5
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Orion AQUAfast Reagent Chemistry Instructions for Orion AquaMate
Thermo Scientific Orion AquaMate Spectrophotometer User Manual | 73
CODH00 COD Mid Range Digestion Tube Test
Dichromate Digestion Method
0 – 1500 mg/l O
2
1. Open one 16 mm COD reaction vial and add 2 ml of deionized water (this is the blank vial).
2. Open a second 16 mm COD reaction vial and add 2 ml of sample (this is the sample vial).
3. Close the vials tightly with the caps and gently invert the vials several times to mix the
contents. CAUTION: The vials will become hot during mixing.
4. Heat the vials for 120 minutes in the preheated reactor at a temperature of 150 °C.
5. CAUTION: The vials will be hot.
Remove the vials from the reactor and allow them to cool to 60 °C or less. Gently invert the
vials several times to mix the contents while still warm. Allow the vials to cool to room
temperature before measuring. Wipe the exteriors of the vials.
6. Load and run the CODH00 method.
7. Place the blank vial into the holder in the sample chamber and close the chamber door.
8. Press the Measure Blank function key to measure the blank.
9. Open the sample chamber door. Remove the blank vial from the holder.
10. Place the sample vial into the holder in the sample chamber and close the chamber door.
11. Press the Measure Sample function key to display the result in mg/l oxygen.
Notes:
• Run samples and blanks with the same batch of vials. The blank is stable when stored in
the dark and can be used for further measurements with vials of the same batch.
• Do not place the hot vials in the sample chamber. Cool the vials to room temperature for
final measurements.
• Suspended solids in the vial lead to incorrect measurements. For this reason, it is
important to place the vials carefully in the sample chamber. The precipitate at the bottom
of the sample should be not suspended.
•
Clean the outside of the vials with a towel. Fingerprints or other marks must be removed.
• Samples can be measured when the chloride content does not exceed 1000 mg/l.
•
In exceptional cases, compounds contained in the water cannot be oxidized adequately, so
results may be lower than reference methods.
•
For samples under 100 mg/l it is recommended to repeat the test using the COD low range
test (CODL00).