Application Note: Establishing Sample Degassing Conditions For The FlowSorb

Sample preparation is crucial in obtaining reliable, repeatable results with the FlowSorb just as it is with all physical adsorption instruments. Users typically establish the temperature-time parameter that gives consistent results by heating samples of the material to be analyzed to various temperatures for different times and then measuring surface areas, or they merely choose temperatures and times that are thought to be more than sufficient. However, one can define what conditions are really required by only a few tests with the FlowSorb itself.

Certain precautions need to be noted before applying the procedure to be described. Do not use this procedure with samples that are contaminated with such things as light hydrocarbons, waxes, or other materials that can decompose and foul the FlowSorb's detector. These materials must be degassed in the usual manner because then they are downstream of the detector and their effluent poses no hazard to the detector. Also certain materials, notably zeolites, must be treated by a several-step procedure because they are known to undergo a structural change if allowed to reflux in their contained water vapor. The procedure with this type of material must be started at no more than 90 °C and increased in increments of approximately 50 °C.

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