Carbon dioxide, respirometer

A different technique utilizes the Warburg respirometer to measure the carbon dioxide liberated by formic acid from a dilute, sodium bicarbonate solution.84 286 Successful application of the method necessitates a pH value of 5.7, which is somewhat high for optimal periodate oxidations, but good results were reported in experiments on a number of materials, including polysaccharides. The procedure is applicable to very small amounts and does not require prior destruction of periodate. 

The reaction is shown as reversible because calculations of the thermodynamics show the release of free energy to be only —7.1 to —2.6 kcal/ mole (4, 77). The actual reversibility of the reaction with this enzyme has not been shown. The activity is generally measured as carbon dioxide formation in a respirometer in the presence of L-malic acid and the cofactors. Lonvaud and Ribereau-Gayon (78) have simplified the method with the use of a carbon dioxide specific electrode. 

ISO CD 14853, Evaluation of ultimate anaerobic biodegradation of plastics materials in an aqueous system- Method of analysis of carbon conversion to carbon dioxide and methane. ISO CD 14854, Evaluation of ultimate aerobic biodegradation of plastics materials in an aqueous system--Method by determining the oxygen demand, biomass and DOC production in a closed respirometer. 

ISO/DlS 17556.2, Plastics. Determination of the ultimate aerobic biodegradabhity in soil by measuring the oxygen demand in a respirometer or the amount of carbon dioxide evolved. 

ISO 17556, Plastics - Determination of the Ultimate Aerobic Biodegradability in Soil by Measuring the Oxygen Demand in a Respirometer or the Amount of Carbon Dioxide Evolved, International Organization for Standardization, Geneva, Switzerland, 2003. 

As for aquatic biodegradation, the first standards for soil biodegradation were developed for simple and pure chemical substances, and published as OECD 304 and ISO 11266. For complex samples such as biodegradable polymers, modifications were needed and first introduced by ASTM D5988-96. In 2003, an ISO Norm was also published ISO 17556 - Plastics - Determination of the ultimate aerobic biodegradability in soil by measuring the oxygen demand in a respirometer or the amount of carbon dioxide evolved. 

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