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 | 67
AC4P72 Chlorine (Total) Powder Pack Test
DPD Method
0.02 – 2 mg/l Cl
2
1. Load and run the AC4P72 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. Add the contents of one Chlorine Total-DPD / 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
(approximately 20 seconds). Wipe the exterior of the vial.
8. Wait for a reaction period of 3 minutes.
9. Place the vial into the holder in the sample chamber and close the chamber door.
10. Press the Measure Sample function key to display the result in mg/l total chlorine.
Notes:
• 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
must be adjusted between pH 6 and pH 7 before the reagent is added (use 0.5 mol/l
sulfuric acid or 1 mol/l sodium hydroxide).
• Exceeding the measuring range: Concentrations above 2 mg/l chlorine using powder packs
can lead to results showing 0 mg/l. In this event, the water sample must be diluted with
water free of chlorine. 10 ml of the diluted sample should be mixed with the reagent and
the measurement repeated.
• Oxidizing agents such as bromine or ozone interfere as they react in the same way as
chlorine.