ion ejection in one embodiment the ion detection system 34 is synchronized to electronic events occurring within the ion storage system 10 for example in one embodiment the operation of the valve 20 is synchronized to at least one of the analog to digital converter 42 and the ion trap power supply 32 by a common clock signal in this embodiment the data sampling is synchronized to the injection of the sample gas synchronizing the valve 20 to electronic events occurring within the ion storage system 10 allows the user to inject sample gas into the volume 30 u2032 of the ion trap cylinder 30 at the appropriate or optimal time in the ion trap cycle injecting the sample gas into the ion trap cylinder 30 at the appropriate or optimal time allows the user to generate the desired pressure profile as a function of time during the ionization period injecting the sample gas into the ion trap cylinder 30 at the appropriate or optimal time can also increase sensitivity reduce background noise and reduce pumping requirements in one embodiment the ion trap power supply 32 and the analog to digital converter 42 are synchronized by a common clock signal in this embodiment the data sampling is synchronized to the termination of the rf field synchronizing the data sampling to the termination of the rf field reduces random noise in the detected ion current and therefore.