Hach DR/850 Procedures Manual page 310

ORGANIC CARBON, TOTAL, High Range,
Accuracy Check
Standard Solutions Method
a. Prepare a 1000 mg/L organic carbon stock standard by
dissolving 2.1254 g dry primary standard Potassium Acid
Phthalate in Organic-Free Reagent Water and dilute to
1000 mL. This stock standard is stable for about 1 month
at room temperature.
Alternatively, open one ampule of TOC Standard
Solution (Cat. No. 27915-05).
b. Prepare a 300 mg/L C standard by transferring 15.00 mL
of the stock standard to a 50-mL Class A volumetric
flask. Dilute to volume using Organic-Free Reagent
Water. Stopper and mix thoroughly. Prepare this standard
fresh weekly.
Standard Additions Method
a. Prepare a 300 mg/L C standard by transferring 18.00 mL
of 1000 mg/L C stock solution to a 50-mL Class A
volumetric flask. Dilute to volume with Organic-Free
Water. Mix.
b. Use the TenSette Pipet to add 0.1, 0.2, and 0.3 mL of the
300 mg/L C standard to each of three Acid
Digestion vials.
c. Add the contents of one TOC Persulfate powder pillow to
each vial.
d. Add 0.3 mL of sample to each vial. Swirl to mix.
e. Proceed with the procedure starting at step 8.
f. The mg/L C concentration should increase by 100 mg/L
for each 0.1 mL increment.
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continued