Gormley-Kennedy equation

Collection Efficiency. Single-Tube Denuders. For the appropriate design of a diffusion-based collection device for an intended application, the ability to estimate the collection efficiency a priori is of considerable help. Although the theoretical soundness of the Gormley-Kennedy equation (equation 1) is not questioned, it is based on the assumption that the uptake probability of the analyte gas at the wall is unity that is, the wall is truly a perfect sink , and every collision results in uptake. This assumption is unrealistic. In recent years, this issue has been reexamined. McMurry and Stolzenburg (42) showed for a liquid-coated denuder how the uptake probability (discussed by the authors in terms of the mass accommodation coefficient ) can be evaluated from collection efficiency measurements. Murphy and Fahey (43) utilized the mathematical solution originally developed for hemodialyzers by Cooney et al. (44) this treatment assumes a constant uptake probability that may be less than unity. To use the Murphy-Fahey approach, however, this probability must be precisely known. 

The fraction deposited is related to the diffusivity by Gormley Kennedy s (1949) equation... 

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