13
XII. XII.
XII. XII.
XII.
Sample HandlingSample Handling
Sample HandlingSample Handling
Sample Handling
• For optimum results, allow samples and standards
and the HI 4105 electrode to reach the same tem-
perature.
• As CO
2
is volatile, measure samples immediately af-
ter collection.
• If sample must be stored: Completely fill collection
bottle with dilute samples and tightly cap container
to prevent carbon dioxide loss or contamination from
other sources.
• If sample must be stored: For acetic samples. add
sodium hydroxide (10N) to raise pH to 8-9 for stor-
age. Tightly close collection bottle.
• If sample must be stored: keep sample at a lower
temperature than it was collected at until time of
measurement.
• Add Hanna HI 4005-00 ISA just prior to measure-
ment to adjust standards and samples to a pH
between 4.2-5.2 for measurement. ISA must mix
thoroughly with solutions and time allowed to convert
carbonate and bicarbonate species to CO
2
(dissolved).
• Covering sample and standards after adding ISA will
minimize carbon dioxide loss from the solution.
• Calibration standards and samples must be the same
ionic strength. The concentration for all dissolved spe-
cies in a sample should not exceed 1M. Samples that
exceed this should
be diluted with CO
2
free deion-
ized water. Do not reduce CO
2
below 10
-4
M. Multiply
the final result by the corresponding dilution factor.
