7
VIIVII
VIIVII
VII.
General GuidelinesGeneral Guidelines
General GuidelinesGeneral Guidelines
General Guidelines
• Calibration standards and sample solutions should
have the same ionic strength. ISA should be added to
both samples and standards immediately before tak-
ing measurements.
• Calibration standards and sample solutions should be
at the same temperature. Thermally insulate solution
vessel from magnetic stirrer with cork or other insulat-
ing medium.
• Calibration standards and sample solutions should
be stirred at the same rate using identical sized stir
bars.
• Surface coating or “wetting“ the PTFE membrane will
effect the response. Inspect sensor before using. Re-
place PTFE membrane if damage is evident.
• Rinse electrode with distilled or deionized water be-
tween samples and dab dry with lab wipe or other soft
disposable absorbent toweling.
• Check calibration every 1-2 hours.
• Position sensors at an angle of approximately 20° to
lessen bubble adherence from solution out-gassing
due to temperature change.
• Close container with plastic wrap or use
HI 4000-71 gas sensor test vessel to prevent gas
from leaving.
• Gently pulling cable will permit an exchange of fill
solution at membrane surface. Re-Calibration is re-
quired.
ions are capable of reducing the ammonia concentration.
If other volumes of sample/standard are used, add ISA at 2
parts per 100 parts standard/sample.
