Samples submitted for Electron Impact (EI) experiments have to be dissolved in a suitable solvent by the operator - normally either dichloromethane or methanol is used, as these will suffice for most organic compounds. The inside of a small glass tube has to be coated with the sample which is then introduced into the EI source via a probe. For the EI source, normal operating conditions are that the source temperature is 150 °C and the source pressure is ca. 10-6 torr ie high vacuum conditions. At present, the highest measurable mass under EI conditions is about 750 daltons (ie m/z value).
For the high resolution EI experiment, the experimental conditions are a bit more tricky and also the subsequent data processing can sometimes take a lot more time to complete - hence one should only ask for accurate mass work if it is really required. The old saying "Think before you submit" springs to mind!
Links to the rest of the Mass Spectrometry Service web pages are listed below for your convenience:-
Please contact Dr Georgina Rosair for further information.