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.
CHEMetrics' leakproof reagent vials contain pre-measured solutions of sulfuric acid and potassium dichromate. To perform the COD determination, the analyst simply removes the TeflonŽ-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°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 directly used in Hach DR/800 Series, DR/2000, and DR/2010 instruments with their pre-programmed calibrations, without the need for a calibration table (Note: No endorsement by Hach Company is implied or intended). Calibration tables for Spectronic 21 instruments are included within the CHEMetrics kit; tables for other instruments are also available.
The CHEMetrics COD kit is packaged in an environment-friendly container holding screw-cap vials, instructions, calibration tables, and MSDS.
