Hartridge spectroscope

Continuous-flow methods allow use of a response time of the recording system longer than the life of the reaction to be followed. As an example, most electrodes have response times of the order of seconds. If they are built into a flow system the time determined by its dimensions and rate of flow will be substituted for the response of the electrode. The analogy with the use of the Hartridge spectroscope is obvious. There have been relatively few applications of the principle. 

The currently employed method of quantifying blood CO and the precaution that is needed for accuracy are simply refinements of the method described by Haldane (1895b, 1896) more than a century ago colorimetric detection was soon replaced by the spectroscopic detection method (Hartridge, 1912) and has undergone further sophistication since then. Both gas chromatography and spectrophotometry are considered appropriate although the former is favored (Cobum et al, 1964 Collison et al, 1968 ... 

Hartridge, H. (1912). A spectroscopic method of estimating carbon monoxide. J. Physiol. 44 1-21. 

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