Statistical Treatment of Isotherms

The principal fact to keep in mind when analyzing an adsorption isotherm is that the pressure reading is invariably much more precise than the 

For example, the linearized BET equation (Eq. (2)) transforms both P/P and but one need only be concerned with the error introduced by. There could be a significant error in the assumed value of P, however the recommendation is to use only values of P between 0.05 and 0.35 of P which eliminates most of this uncertainty. Since the function used in is l/n then the error is approximated by where s is the error 

The problems of interpretation of statistical parameters and error introduced by data transformation are not present in the standard isotherms, such as the a-s plot, t-plot or others, nor are they problems with the X plot. In these cases, n remains untransformed and the error for the full range is approximately constant. A straight application of a simple linear regression is therefore appropriate. This makes the derived statistics, such as standard deviation, R, etc., easy and straightforward to interpret. These statistics then relate directly to the physical quantities that they are associated with. 

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