NEMI Method Summary


Method Summary Information

Method Number:

I-3561

Media:

WATER

Revision:

1985

Method Source:

U.S. Geological Survey (USGS)

Subcategory:

ORGANIC

Analytes in this method

Official Name:

Total Chemical Oxygen Demand in Water-Suspended Sediment by Dichromate Oxidation and Colorimetry

Descriptive Name

Chemical-oxygen-demand, water-suspended-sediments, colorimetry

Source Info:

USGS Branch of Information Services
Box 25286, MS 417
Federal Center
Denver, CO 80225-0286
Phone: 303-202-4700

Citation:

USGS Methods, Volume A1

111428

Byte file

Brief Method
Summary:

Organic and other oxidizable materials are oxidized by digestion with an acid-dichromate solution in the presence of silver sulfate catalyst. The COD concentration is determined spectrometrically by measuring the absorbance of the Cr+3 that is formed.

Scope And
Application:

This method may be used to analyze water-suspended sediment containing between 10 and 500 mg/L chemical oxygen demand (COD).

Applicable
Conc Range:

10 - 500mg/L

Interferences:

(1) Chloride ion, and other halides that precipitate silver. (2) Incomplete oxidation of nitrogen-containing organic matter. (3) Nitrite ion. (4) Reduced inorganic species (e.g., ferrous iron, sulfide, manganous manganese).

QC Requirements:

Calibrate instrument using calibration standards (CAL). Quality control samples (QCS) and laboratory blanks (LB) analyzed at a minimum of I each after every 10 samples. (Reference OFR 95-443)

Sample Handling:

Container Description: 125 mL Glass bottle
Treatment and Preservation: Bottle baked at 450 deg C by laboratory. Prepare each sample to pH<2 with H2SO4; chill and maintain at 4 deg C. DO NOT RINSE BOTTLE.

Max Holding Time:

Relative Cost:

Less than $50

4765

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Method Summary Information