Properties of acrylonilrile-butadiene-rubber (NBR) are determined by the acrylonitrile content of the NBR. Very often it is necessary to know the AN content of the NBR rubber: The integrated TGA-FTIR-System is used to analyze uncured NBR types with different AN content A sample of uncured NBR is analyzed to show for example which sorts of results one can get with this integrated analytical system. Several uncured NBR types with AN contents in the range between 18 and 48% are analyzed to decide whether a distinction is possible.