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
110 | Orion AquaMate Spectrophotometer User Manual Thermo Scientific
AC4P60 Silica Powder Pack Test
Silicomolybdate Method
1 – 90 mg/l SiO
2
1. Load and run the AC4P60 method.
2. Fill a clean AQUAfast 24mm round vial, Cat. No. AC2V24, with 10 ml of sample.
Temperature of the sample should be 15 °C to 25 °C. Close the vial tightly with the cap.
Wipe the exterior of the vial.
3. Place the vial into the holder in the sample chamber and close the chamber door.
4. Press the Measure Blank function key to measure the blank.
5. Open the sample chamber door and remove the vial from the holder.
6. Add the contents of one Silica HR Molybdate F10 Powder Pack straight from the foil into
the vial.
7. Close the vial tightly with the cap and swirl or invert several times to mix the contents.
8. Add the contents of one Silica HR Acid Rgt. F10 Powder Pack straight from the foil into the
same vial. If silica or phosphate is present, a yellow color will develop.
9. Close the vial tightly with the cap and swirl or invert several times to mix the contents.
10. Wait for a reaction period of 10 minutes.
11. Add the contents of one Silica Citric Acid F10 Powder Pack straight from the foil into the
same vial. In this step, any yellow color due to phosphate is removed.
12. Close the vial tightly with the cap and swirl or invert several times to mix the contents. Wipe
the exterior of the vial.
13. Wait for a reaction period of 2 minutes.
14. Place the 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 silica.
Notes:
• Occasionally water samples contain forms of silica which reacts very slowly with
molybdate. The nature of these forms is not known.
•
A pre-treatment with sodium hydrogen carbonate and then with sulfuric acid will make
these forms reactive to molybdate (pre-treatment is given in “Standard Methods for the
Examination of Water and Wastewater” under “Silica Digestion with Sodium Bicarbonate”).
Substance Interference
Iron Large amounts interfere
Phosphate Does not interfere at concentrations less than 50 mg/l PO
4
At 60 mg/l PO
4
the interference is approximately 2%
At 75 mg/l PO
4
the interference is approximately 11 %
Sulfide Interferes at all levels