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 | 71
CODL00 COD Low Range Digestion Tube Test
Dichromate Digestion Method
0 – 150 mg/l O
2
1. Open one 16 mm COD reaction vial and add 2 ml of deionized water (this is the reagent
blank vial).
2. Open a second 16 mm 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 CODL00 method.
7. Fill a clean AQUAfast 16mm round vial, Cat. No. AC2V16, with deionized water (this is the
blank vial). Close the vial tightly with the cap. Wipe the exterior of the vial.
8. Place the blank vial into the holder in the sample chamber and close the chamber door.
9. Press the Measure Blank function key to measure the blank.
10. Open the sample chamber door. Remove the blank vial from the holder.
11. Place the reagent blank vial into the holder in the sample chamber and close the chamber
door.
12. Press the Measure Rgnt Blank function key to measure the reagent blank.
13. Open the sample chamber door. Remove the reagent blank vial from the holder.
14. Place the sample vial into the holder in the sample chamber and close the chamber door.
15. Press the Measure Sample function key to display the result in mg/l oxygen.
Notes:
•
Reverse color methods use a reagent that, when prepared with samples, deceases in color
as the concentration of the species being measured in the samples increases. Reverse
color methods require the use of both a blank and a reagent blank. The blank is a clear
solution (deionized water) with zero absorbance. The reagent blank is a mixture of the
reagent and deionized water and provides a zero concentration point with the darkest color
(highest absorbance). The color of samples prepared with the reagent will decrease as the
concentration increases for this method.