Color, ADMI DOC316.53.

01122

ADMI Weighted Ordinate Method1, 2 Method 10048

5 to 1000 Pt-Co units3
Scope and application: For water and wastewater. Turbid samples are filtered during the analysis.
1 Adapted from Allen, et al., 1972. Determination of color of water and wastewater by means of ADMI Color Values. Proc. 28th Ind. Waste
Conf., Purdue Univ., Eng. Ext. Ser. no. 142:661.
2 Procedure is equivalent to Standard Method 2120 F.
3 DR5000: 5 to 250 Pt-Co units

Test preparation

Instrument-specific information
Table 1 shows all of the instruments that have the program for this test. The table also
shows the sample cell options and orientation requirements.
To use the table, select an instrument, then read across to find the applicable information
for this test.
Table 1 Instrument-specific information
Instrument Sample cell orientation 1-inch sample cell 10-mm sample cell 50-mm sample cell
DR6000 The fill line is to the right (1-inch cell) 2495402 2095100 2629250
The clear side is to the right (10-mm, 50-mm
cells)
DR5000 The fill line is toward the user (1-inch cell)
DR3900 The clear side is toward the user (10-mm, 50-
mm cells)

Before starting
Review the Safety Data Sheets (MSDS/SDS) for the chemicals that are used. Use the recommended personal protective
equipment.
Dispose of reacted solutions according to local, state and federal regulations. Refer to the Safety Data Sheets for disposal
information for unused reagents. Refer to the environmental, health and safety staff for your facility and/or local regulatory
agencies for further disposal information.

Items to collect
Description Quantity

Beaker, 250 mL polypropylene 2

Cylinder, graduated, 100 mL polypropylene 1
Filtration apparatus: funnel/filter holder, 0.45 µm filter, flasks (2) and aspirator 1
pH meter with electrode 1
Sodium hydroxide or sulfuric acid solution, 10 N and 0.100 N varies
Water, deionized varies
Sample cells (For information about sample cells, adapters or light shields, refer to Instrument-
2
specific information on page 1.)

Refer to Consumables and replacement items on page 4 for order information.

1
Sample collection
• Collect samples in clean glass or plastic bottles with tight-fitting caps. Completely fill
the bottle and immediately tighten the cap.
• Prevent agitation of the sample and exposure to air.
• Analyze the samples as soon as possible for best results.
• If immediate analysis is not possible, keep the samples at or below 6 °C (43 °F) for a
maximum of 24 hours.
• Let the sample temperature increase to room temperature before analysis.

Test procedure

Start

1. Start program 2. Pour 100 mL of sample 3. Adjust the pH of the 4. If the sample is turbid,
96 Color ADMI 10 mm into each of two beakers. sample in one of the set up the filtration
beakers to pH 7.6 with a apparatus (0.45 micron
97 Color ADMI 1 inch or
minimum volume of sodium membrane filter, filter
98 Color ADMI 50 mm hydroxide or sulfuric acid holder/funnel, filter flask,
depending on the sample solution. Use a 10 N and aspirator). If the sample
size. For information about solution to make large pH is not turbid, go to step 10.
sample cells, adapters or adjustments and a 0.1 N
light shields, refer to solution to make small pH
Instrument-specific adjustments.
information on page 1. Note: Sodium hydroxide
increases the pH value and
sulfuric acid decreases the
pH value.

5. Pour approximately 6. Pour the remaining 7. Install a clean filter flask 8. Pour approximately
50 mL of the original sample 50 mL of original sample for the pH-adjusted sample. 50 mL of the pH-adjusted
through the filter to rinse the through the filter. sample through the filter.
filter. Discard the rinse Write "original" on the flask. Discard the rinse water.
water.

2 Color, ADMI Method

9. Pour the remaining 10. Prepare the blank: Fill 11. Prepare the sample: 12. Clean the blank sample
50 mL of pH-adjusted a sample cell with deionized Fill a second sample cell cell.
sample through the filter. water. with the pH-adjusted
Write "pH-adjusted" on the sample. Discard the
flask. remaining sample in the
flask.

Zero

13. Insert the blank into the 14. Push ZERO. The 15. Clean the prepared 16. Insert the prepared
cell holder. display shows the scan sample cell. sample into the cell holder.
status, then 0 ADMI Value.

Read

17. Push READ. Results 18. Do steps 11 to 17 again

show in ADMI Value. for the original sample.
For USEPA reporting, report
both results.

Interferences
Turbidity interferes directly. The filtration steps in the test procedure remove turbidity.
Accuracy check
Standard solution method
Use the standard solution method to validate the test procedure, the reagents and the
instrument.
Items to collect:
• Color standard solution, 500 platinum-cobalt units
• 100-mL volumetric flask, Class A
• 20-mL volumetric pipet, Class A and pipet filler

Color, ADMI Method 3

 • Deionized water

1. Prepare a 100 platinum-cobalt units standard solution as follows:

a. Use a pipet to add 20.00 mL of a 500 platinum-cobalt units standard solution into
the volumetric flask.
b. Dilute to the mark with deionized water. Mix well.
2. Use the test procedure to measure the concentration of the prepared standard
solution.
3. Compare the expected result to the actual result.
Note: The factory calibration can be adjusted slightly with the standard calibration adjust option
so that the instrument shows the expected value of the standard solution. The adjusted
calibration is then used for all test results. This adjustment can increase the test accuracy when
there are small variations in the reagents or instruments.

Summary of method
The three properties of color are hue, chroma and value. Hue is the color name, such as
blue, red, green or yellow. Chroma is the color intensity (e.g., bright or dull). Value is how
light or dark the color is. This method measures the color value independently of the hue
and the chroma.
The sample transmittance is measured from 400 to 700 nm. The transmittance values are
calculated to give a set of numbers for the color that is seen by typical humans. Further
calculations give a single number for the color value. This number can be found on a
scale used by the American Dye Manufacturers Institute (ADMI) for color value. The
ADMI uses the platinum-cobalt standard from the American Public Health Association
(APHA) as the standard for color value. Although this standard is yellow, the ADMI
method is applicable to all hues.
Consumables and replacement items
Required reagents

Description Quantity/test Unit Item no.

Sodium Hydroxide Solution, 10 N varies 500 mL 2545049

Sodium Hydroxide Standard Solution, 0.100 N varies 1000 mL 19153
Sulfuric Acid, 10 N varies 1000 mL 93153
Sulfuric Acid Standard Solution, 0.100 N varies 100 mL MDB 20232H
Water, deionized varies 4L 27256

Required apparatus

Description Quantity/test Unit Item no.

Beaker, polypropylene, 250 mL 2 each 108046

Cylinder, graduated, polypropylene, 100 mL 1 each 108142
pH meter with electrode 1 each HQ11d

Recommended standards

Description Unit Item no.

Color standard solution, 500 platinum-cobalt units 1L 141453

4 Color, ADMI Method

Optional reagents and apparatus

Description Unit Item no.

Filter pump, aspirator each 213100

Filter holder, magnetic each 1352900
Filter membrane, 0.45 micron, 47 mm 100/pkg 1353000
Flask, filtering, 500 mL each 54649
Flask, volumetric, Class A, 100 mL each 1457442
Pipet, volumetric Class A, 20 mL each 1451520
Pipet filler, safety bulb each 1465100
Stopper, rubber, one-hole, No. 7 6/pkg 211907
Tubing, rubber, 5/16-in. inside diameter 3.66 m (12 ft) 56019

Color, ADMI Method 5

 FOR TECHNICAL ASSISTANCE, PRICE INFORMATION AND ORDERING: HACH COMPANY
In the U.S.A. – Call toll-free 800-227-4224 WORLD HEADQUARTERS
Outside the U.S.A. – Contact the HACH office or distributor serving you. Telephone: (970) 669-3050
On the Worldwide Web – www.hach.com; E-mail – techhelp@hach.com FAX: (970) 669-2932

© Hach Company/Hach Lange GmbH, 2007–2015, 2017, 2019. All rights reserved. 12/2019, Edition 11