Ionics Instruments 2004 Page E - 4 DLM 30007-08 Rev. A
18. If preparing standards on site, fill a 1-L volumetric flask with low TOC,
DI water. If using Ionics Instruments-prepared standards, use a vial
labeled Reagent Water. Place the 1/16"-OD INLET Teflon tube in the
flask or vial, making sure the end of the tubing is several inches
below the liquid level.
WARNING
Do not use a beaker for measuring the TC background of the water. Measure
the water immediately after filling the flask. If the water is allowed to stand
exposed to air for more than an hour, the water will absorb atmospheric CO
2
and record a high TC background.
19. From the Grab Sampling menu, use the arrows ( or ) to scroll to
START and press ENTER.
20. The analyzer will make exactly 10 measurements. When the
measurements are finished, the average TC value and relative
standard deviation for the last three measurements will be shown on
the LCD display.
21. Record the average value from the last three
TC measurements as
shown on the analyzer display. If the value displayed is in ppb,
convert to ppm by dividing the ppb value by 1000.
Average TC value from last three runs (ppm C) ______________
This background TC value will be added to the calculated
concentration of the dilute TC standard in Part Three.
Part 2 – Prepare a Stock TC Standard
Place a small quantity (1-2 grams) of anhydrous potassium hydrogen
phthalate in a beaker and dry in an oven at 110° C for 2-3 hours. Transfer the
beaker to a desiccator and allow the sample to cool.
Weigh out approximately 0.212 grams of anhydrous potassium hydrogen
phthalate (dried to a constant weight). Record the weight. Dissolve in a 100
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