6
A user supplied oxidizing reagent may be used to supress
interferences such as hydroxide, sulfide, bromide, ammo-
nia or cyanide . Add 10 mL to 100 mL standard or sample.
Permit sample to mix 10 minutes before measurements are
taken. Discard samples and standards promptly as the
chloride in these will oxidize upon standing making them
unrelible. Do not permit electrodes to remain in this solu-
tion for long periods of time. Work in a hood and protect
eyes and skin. Prepare oxidizing reagent by diluting 6.25
mL analytical grade concentrated nitic acid into approxi-
mately 800 mL deionized water. Mix carefully. Dilute to 1
liter.
VII
VII
VII
VII
VII. General Guidelines
General Guidelines
General Guidelines
General Guidelines
General Guidelines
•
Calibration standards and sample solutions should
have the same ionic strength. ISA, acetate buffer or
oxidizing reagent should be added to both samples
and standards in the same ratio.
•
Calibration standards and sample solutions should
be at same temperature.
•
Thermally insulate beaker with standard or sample
from magnetic stirrer.
•
Calibration standards and sample solutions should
be stirred at the same rate using identical sized TFE
coated stir bars.
•
Rinse electrode pair with distilled or deionized water
between samples and gently dry off using soft dis-
posable absorbent toweling. Do not rub sensor sur-
face.
•
Presoaking chloride sensor in a dilute standard will
optimize response. Do not use concentration above
10
-3
M.
•
A scratched, pitted, or tarnished pellet surface can
cause drift, a loss of low level response, or poor repeat-
ability. Optimum response can be restored by remov-
ing the damaged surface with the microabrasive strip
HI 4000-70.