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
62 | Orion AquaMate Spectrophotometer User Manual Thermo Scientific
AC2071 Chlorine (Free) Tablet Test
DPD Method
0.01 – 6 mg/l Cl
2
1. Load and run the AC207124 method.
2. Fill a clean AQUAfast 24mm round vial, Cat. No. AC2V24, with 10 ml of sample. 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. Empty the vial, leaving a few drops of sample remaining in the vial.
7. Add one DPD No. 1 Tablet straight from the foil into the vial. Crush the tablet with a clean
stir rod.
8. Add sample to the 10 ml mark on the vial.
9. Close the vial tightly with the cap and swirl or invert several times until the tablet is
dissolved. Wipe the exterior of the vial.
10. Place the 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 free chlorine.
Notes:
•
Alternatively, the AC207110 method can be used with 10mm square vials and the
AC207150 method can be used with 50mm rectangular vials. All blank and sample
volumes must remain the same as those specified in these instructions, so samples may
need to be prepared in separate containers and then transferred into the selected vial.
•
Vial cleaning: As many household cleaners (i.e. dishwasher detergent) contain reducing
substances, the subsequent determination of chlorine may show lower results. To avoid
any measurement errors, only use glassware free of chlorine demand.
Preparation: Put all applicable glassware into sodium hypochlorite solution (0.1 g/l) for one
hour and then rinse all glassware thoroughly with deionized water.
• For individual testing of free and total chlorine, the use of different sets of glassware is
recommended (EN ISO 7393-2, 5.3).
• Preparing the sample: When preparing the sample, the escape of chlorine gases, i.e. by
pipetting or shaking, must be avoided. The analysis must take place immediately after
taking the sample.
•
The DPD color development is carried out at a pH value of 6.2 to 6.5. The reagents
therefore contain a buffer for the pH adjustment. Strong alkaline or acidic water samples