DR/2400
Color, True and Apparent
ColorTru_None_Other_PCS_Eng_Ody.fm Page 1 of 4
• NCASI procedure requires pH adjustment. Adjust the pH to 7.6 with 1.0 N HCl or 1.0 N NaOH. When adjusting the pH, if overall
volume change is greater than 1%, start over and use a stronger acid or base.
• Wipe the outside of sample cells before each insertion into the instrument cell holder. Use a damp towel followed by a dry one to
remove fingerprints or other marks.
• To test for apparent color, omit steps 3, 4, 5, and 7. Do not filter the sample. Use unfiltered deionized water for the blank.
Color, True and Apparent
Method 8025
Platinum-Cobalt Standard Method* **
*Adapted from Standard Methods for the Examination of Water and Wastewater and NCASI, Technical Bulletin No. 253, Dec. 1971
** Adapted from Wat. Res. Vol. 30, No. 11, pp. 2771–2775, 1996
(5 to 500 units)
Scope and Application: For water, wastewater, and seawater; equivalent to NCASI method 253 for pulp
and paper effluent using 465 nm (requires pH adjustment)
1. Touch
Hach Programs.
Select program
120 Color, 455 nm
or
125 Color, 465 nm.
Touch
Start.
Note: Use Hach program 125
when performing the NCASI
procedure.
2. Collect 200 mL of
sample in a 400-mL
beaker. For the NCASI
procedure, adjust the pH
as described above.
3. Assemble the filtering
apparatus (0.45 micron
membrane filter, filter
holder, filter flask, and
aspirator).
Note: NCASI prescribes a
0.8-micron filter.
4. Rinse the filter by
pouring about 50 mL of
deionized water through
the filter. Discard the
rinse water.
Tips and Techniques
10 mL
Method 8025
Hach Programs
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