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
70 | Orion AquaMate Spectrophotometer User Manual Thermo Scientific
10. Close the vial tightly with the cap and swirl or invert several times until the tablets are
dissolved. Wipe the exterior of the vial.
11. Place the vial into the holder in the sample chamber and close the chamber door.
12. Press the Measure Sample function key to display the result in mg/l chlorine dioxide.
Notes:
• Alternatively, the AC209950 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 dioxide 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.
•
Preparing the sample: When preparing the sample, the escape of chlorine dioxide 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 reagent tablet
therefore contains a buffer for the pH adjustment. Strong alkaline or acidic water samples
must be adjusted between pH 6 and pH 7 before the tablet is added (use 0.5 mol/l sulfuric
acid or 1 mol/l sodium hydroxide).
• Exceeding the measuring range: Concentrations above 19 mg/l chlorine dioxide can lead to
results showing 0 mg/l. In this event, the water sample must be diluted with water free of
chlorine dioxide. 10 ml of the diluted sample should be mixed with the reagent and the
measurement repeated.
• Oxidizing agents such as chlorine or ozone interfere as they react in the same way as
chlorine dioxide.