A gas handling technique has been developed for metering CO 2 into the gas ion source of the Erlangen AMS facility. Further investigations and developments have resulted in a system that enables the handling of gaseous samples with carbon masses from 1 lg to 1 mg. The system has been optimized for coupling an elemental analyzer to a gas ion source. Moreover, the system can be connected to any other system that produces CO 2 , e.g. gas ampoules, gas chromatographs, etc. The principle of the gas handling system is to first store and isolate CO 2 cryogenically. Then the CO 2 is fed into the ion source by the pressure difference between the CO 2 reservoir and the gas ion source which are connected by a glass capillary. By regulation of the CO 2 pressure, the CO 2 flow into the ion source can be controlled. The outstanding advantage of this easy technique is the possibility of its complete automation. For use of the system with an elemental analyzer we created application software that controls the combustion of the sample, the cryogenic storage and the exact metering of the CO 2 into the ion source. Besides the application of using CO 2 for radiocarbon dating, our gas handling system opens new possibilities of research in fields where only small samples are available or large series of samples have to be measured quickly, e.g. environmental or biomedical research. In addition this system has turned out to be a perfect tool for detailed investigations of gas ion sources.