Abstract: In using partially alkali metal exchanged forms of FAU zeolite as selective adsorbents for use in insulated glass windows, particularly for use in a matrix in insulated glass windows, it has been discovered that significant reduction in the nitrogen loading on the zeolite results when the alkali metal content is maintained at a low level. For example, such FAU zeolites, particularly zeolite X which has been ion-exchanged with potassium ions to a level of between about 5 and about 75 equivalent mole percent indicate a nitrogen adsorption loading of between about 400 and 600 percent lower than unexchanged zeolite X and about 200 percent less than fully potassium exchanged zeolite X. The adsorbent is particularly useful in a sealant matrix for insulated glass windows and may be used in combination with zeolite A to reduce out-gassing problems.