Hach DR/850, Руководство по процедурам, Страница: 302 / 460

302
ORGANIC CARBON, TOTAL, Mid Range,
continued
Sampling and Storage
Collect samples in clean glass bottles. Rinse the sample bottle several times with the sample to
be collected. Fill the bottle with minimum headspace before capping. Test samples as soon as
possible. Acid preservation is not recommended. Homogenize samples containing solids to
assure representative samples.
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 100 mg/L C standard by transferring 5.00 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 15.00 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 1.0 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 30 mg/L for each 0.1 mL increment.