Hach DR/850, Procedures Manual, Page: 229 / 460

229
Samples containing high levels of both Total Hardness and
Alkalinity may become turbid (cloudy) after the addition of the
Free Ammonia Reagent Solution. If this occurs by the end of the
first reaction period, the sample for Free Ammonia measurement
must be pretreated as follows:
Note: The sample for
Monochloramine
measurement does not need
pretreatment.
1. Measure 10 mL of sample into the cell for Free Ammonia
measurement.
2. Add the contents of one Hardness Treatment Reagent Powder
Pillow (Cat. No. 28823-46) to the sample.
3. Cap the cell and invert until the reagent is dissolved.
4. Remove the cap.
Continue with the analysis at step 2 using the pretreated sample
as the Free Ammonia cell.
Accuracy Check (Monochloramine, Program 110)
1. Prepare the following monochloramine standard fresh before
use.
2. Add the contents of one Buffer Powder Pillow, pH 8.3 to
about 50-mL of organic-free water in a clean 100-mL Class A
volumetric flask. Swirl to dissolve the powder.
3. Using a Class A volumetric pipet, transfer 2.00 mL of
Nitrogen, Ammonia Standard Solution, 100 mg/L as NH
3
–N
into the flask.
Substance Level Tested
Aluminum 0.2 mg/L Al
Chloride 1200 mg/L Cl
Copper 1 mg/L Cu
Iron 0.3 mg/L Fe
Manganese 0.05 mg/L Mn
Nitrate 10 mg/L NO
3
–N
Nitrite 1 mg/L NO
2
–N
Phosphate 2 mg/L –PO
4
Silica 100 mg/L SiO
2
Sulfate 1600 ppm as CaCO
3
Zinc 5 ppm Zn
Nitrogen, Free Ammonia and Chloramine (Mono), continued