Chemical Oxygen Demand (COD)
References: USEPA Methods for Analysis of Waters & Wastes , method 410.4 (1983).
APHA Standard Methods, 20th ed., p. 5-17, method 5220 D (1998).
A.M. Jirka and M.J. Carter, "Micro Semi-Automated Analysis of Surface and Wastewaters for Chemical Oxygen Demand", Analytical Chemistry, Vol. 47, p. 1397 (1975).
J.A. Winters, "Method Research Study 3, Demand Analysis, An Evaluation of Analytical Methods for Water and Wastewater," USEPA (1971)
ASTM D 1252-00, Chemical Oxygen Demand (Dichromate Oxygen Demand) of Water, Test Method B

Call 1-800-356-3072 for USEPA certificate of equivalency.

COD Instruction Booklet

The determination of Chemical Oxygen Demand (COD) is widely used in municipal and industrial laboratories to measure the overall level of organic contamination in wastewater. The contamination level is determined by measuring the equivalent amount of oxygen required to oxidize organic matter in the sample.

The Colorimetric Method. 
CHEMetrics offers two reactor digestion (micro) methods for fast, easy, safe determinations of low-, mid-, and high-range COD levels in wastewater: (1) the USEPA-approved method*, and (2) a mercury-free method. The products using the USEPA-approved method contain mercuric sulfate in the reagent to eliminate chloride interferences. The more readily disposable mercury-free product line is applicable when chloride interference is not a concern and USEPA reporting is not required.  The mercury-containing 0-15,000 ppm reagent is not USEPA approved and should not be used for NPDES reporting. 

CHEMetrics' leakproof reagent vials contain pre-measured solutions of sulfuric acid and potassium dichromate. To perform the COD determination, the analyst simply removes the Teflon®-lined screw cap from the vial, adds sample to the vial, and replaces the cap. The vial is then heated for two hours at 150 deg. C in a standard digestor block. Once digestion is completed, results are obtained using any photometer that accepts 16-mm diameter cells.

CHEMetrics' COD vials can be used with any Hach instrument that is pre-programmed for dichromate digestion without the need for a calibration table (Note: No endorsement by Hach Company is implied or intended). Calibration tables for use with other spectrophotometers are included in the CHEMetrics COD instruction booklet.

The CHEMetrics COD kit is packaged in an environment-friendly container holding screw-cap vials, instructions, calibration tables, and MSDS. Accessories, including calibration standards, digestors, vial racks, and safety shields may be purchased separately.

*Contains mercury.  Dispose according to local, state or federal laws.