Sealed Vessel Test

The evolution of the biodegradation screening test - Smaller is Better

Limitations exist for biodegradation screening tests that rely on oxygen uptake or dissolved organic carbon (DOC) disappearance as evidence of biodegradation. These measurements provide only indirect evidence for ultimate biodegradability and problems can develop when insoluble or volatile chemicals are studied. Oxygen uptake studies can also give false positive results. Measurement of evolved carbon dioxide (or carbon dioxide and methane for anaerobic systems) is the preferred assay because these products represent direct degradation products rather than disappearance of a precursor. For these reasons, Springborn will generally recommend carbon dioxide evolution studies for biodegradability screening.

For years, the Modified Sturm (OECD 301B) and the EPA 796.3100 aerobic aquatic biodegradation test ("Gledhill Test") have been the carbon dioxide evolution studies of choice. Recently, more cost effective methodologies have been forwarded by the American Society for Testing and Materials (ASTM 1720-95), the International Standardization Organization (ISO/DIS 14593) and the EPA's Office of Prevention, Pesticides and Toxic Substances (OPPTS 835.3120). These tests involve use of sealed vessels (160 mL instead of the conventional 4-L bottle for the OECD 301B test). Smaller vessels are more cost effective, allow greater replication and eliminate problems associated with retention of carbon dioxide in the test medium.

With the advent of automated carbon analyzers, Springborn has miniaturized the current sealed vessel test to 20-mL test vessels. Use of these vessels coupled with an automated carbon analyzer capable of measuring headspace carbon dioxide allows multiple chemicals and replicates to be analyzed for a fraction of the cost of the 301B. Furthermore, biodegradation results obtained from replicates are very similar.

Utilizing our new 20-mL test vessels, Springborn can provide cost effective testing for Product Stewardship. Studies can be customized to address your specific environmental concerns.