Respirometer, Warburg

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. 

For reactions in which one or more reactants or products is a gas, manometry (the measurement of pressure differences) can provide a convenient means for monitoring the course and kinetics of the reaction Thus, enzymes that can be assayed with this method include oxidases, urease, carbonic anhydrase, hydrogenase, and decarboxylases. For example, bacterial glutamate decarboxylase is readily assayed by utilizing a Warburg flask and measuring the volume of gas evolved at different times using a constant-pressure respirometer. ... 

Rates of Hs uptake were measured in Warburg respirometers at 1°. After gassing the vessels with H2 and before mixing with KCN and CoCl solutions, traces of O2 were removed by an oxygen absorber in the center well of each vessel. No buffer was employed in the Warburg experiments reported here. 

The biological breakdown of Sevin in Nile River water and 50% sewage was also studied by measuring the oxygen uptake with the Warburg Respirometer see Figure 13). Sevin in concentration of 40 mg/ liter was rapidly oxidized in Nile water after a lag period of one day, and the oxygen uptake reached 95% of the theoretical amount required... 

A. S. Perlin, Production of formic acid during oxidation of carbohydrates with lead tetraacetate, J. Am. Chem. Soc., 76 (1954) 5505-5508 A. S. Perlin, Oxidation of carbohydrates with periodate in the Warburg respirometer, J. Am. Chem. Soc., 76 (1954) 4101 103. 

Holman and Elmer (1947) neat methyl or ethyl esters were autoxidized at 37°C and rates were measured by oxygen absorption with a Warburg respirometer. 

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