Saving time when measuring BET isotherms

The measurement of adsorption isotherms and the determination of surface properties of a solid by means of the BET equation usually takes a lot of time as it involves measurement of several dynamic adsorption curves each at a given gas pressure. Two different timesaving approaches are suggested: (a) the beginning of a single dynamic curve is considered and (b) the beginnings of a number of different dynamic curves is considered. Approach (a) is less time consuming than approach (b), where approach (b) yields more accurate estimates of the BET-parameters. A discussion is given of the possibilities of using the time saving procedure of Jäntti for the two approaches.