Why do free chlorine results differ on the SL1000 when compared to the powder pillow methods?

Document ID

Document ID TE8408

Version

Version 1.0

Status

Status Published

Published Date

Published Date 01/10/2018
Question
Why do free chlorine results differ on the SL1000 when compared to the powder pillow methods?
Summary
SL1000 results differ from powder pillow methods
Answer
There are a few factors that can result in differences in free chlorine results when comparing SL1000 results to powder pillow methods on colorimeters or spectrophotometers.
  • Chemkey reagents reduce many elements of human error or variability present in powder pillow tests: shaking time, reaction time, vial cleanliness, etc. 
    • Standardization of the measurement processes means that Chemkey results are more precise and repeatable.
  • Sample temperature: the SL1000 has automatic temperature control, eliminating differences in sample temperature which can result in variability.
  • Elimination of monochloramine interference: the free chlorine Chemkey has mitigated monochloramine as an interference in free chlorine tests; powder pillow methods still have this interference.
  • Elimination of outliers: the SL1000 takes multiple blank and sample measurements with each Chemkey, allowing the instrument to discard outliers and provide more accurate results.
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