Convenient & Safe COD Results Using SPECTRONIC^® Spectrophotometers and the Bioscience ACCU-TEST^® System

WHAT IS THE COD TEST?

Oxygen demand is a significant parameter for determining the effect of organic pollutants on water. As micro-organisms in the environment ingest the organic material, oxygen is depleted. This, in turn, will result in harm to fish and plant life. 

The determination of the Chemical Oxygen Demand (COD) is used as a measure of the oxygen equivalent of the organic matter content of a sample that is susceptible to oxidation by a strong chemical oxidant. 

The colorimetric, dichromate reflux method has been the most common method of determining the COD content in a sample, and has been preferred over procedures using other oxidants because of superior oxidizing ability, applicability to a wide variety of samples, and ease of manipulation (see Standard Methods for the Examination of Water and Wastewater, AWWA-APHA-WPCF, 17th edition, Washington, D.C., 1989).

THE BIOSCIENCE COD ACCU-TEST^® SYSTEM 

Bioscience, Inc. offers a test system which uses a semi-micro version of the Standard Methods procedure for the determination of COD which is more convenient, uses much less dichromate reagent and is approved by the Environmental Protection Agency for NPDES reporting. 

Bioscience's EPA-Accepted ACCU-TEST^® Chemical Oxygen Demand system consists of COD reagent vials, a heating block and a data management software package. 

In the Bioscience COD ACCU-TEST^® system, the test sample is added to a small amount of dichromate reagent in a reagent vial (screw capped tube) and then incubated in a COD reactor (heating block). After the pollutants in the sample are oxidized by the dichromate, the tubes are transferred unopened to a spectrophotometer. 

The spectrophotometric readings are used with a calibration graph to determine the COD of the test sample. 

The Bioscience COD ACCU-TEST^® systems come in three sensitivity ranges for spectrophotometry: 5-150 mg/L (440nm), 20-900 mg/L (600nm), and 100-4500 mg/L (600nm). Bioscience, Inc. has recently added a mercury-free product designed to reduce waste disposal costs for customers with low chloride content test samples. COD standard solutions are also available.

HOW IS IT USED WITH THERMO SPECTRONIC SPECTROPHOTOMETERS? 

Any SPECTRONIC^® spectrophotometer may be used in conjunction with the Bioscience, Inc. reagent vials. 

Microprocessor-controlled spectrophotometers such as the SPECTRONIC^® 401, GENESYS^TM 5, or GENESYS^TM 2 have built-in standard curve test modes. The Bioscience ACCU-TEST^® Vials and COD reactor can be used to create and store a COD calibration curve in the permanent memory of the spectrophotometer. The COD calibration curve can be retrieved when needed to automatically convert the absorbance readings of the unknown samples to COD concentration units. The ACCU-TEST^® vials and reactor can then be used to test unknowns. 

To use the Bioscience COD vials in the SPECTRONIC^® 401, both the Test Tube Holder (Cat. No. 335414) and the Light Shield (Cat. No. 335410) are required. The GENESYS^TM 2 or GENESYS^TM 5 require the Cell Holder Platform (Cat. No. 335626) and its Test Tube Holder (Cat. No. 336014). 

Bioscience, Inc. has also developed a PC-based COD data-management software package that operates with the SPECTRONIC^® 20D, SPECTRONIC^® 21DV, and the SPECTRONIC^® 21DUV. The software package runs on an IBM-compatible PC connected to one of these three spectrophotometers. The software automates data acquisition, calibration, COD calculations, QA/QC, reporting and data storage and retrieval. 

All SPECTRONIC^® 20 series spectrophotometers include a test tube holder which will accept the Bioscience COD vials without any additional adapters. The SPECTRONIC^® 21 series of instruments require a Light Shield (Cat. No. 335410).

INFORMATION 

More information about the ACCU-TEST^® Chemical Oxygen Demand system is available from Bioscience, Inc., 610-974-9693 or 800-627-3069.