Abstract: In this work the mixture of high-ionization potential element Mg andrare-earth element Gd is placed on the filament, then the isotopes of the ele-ments can be analysed at a time. Satisfactory and stable beam intensity canbe maintained for more than one hour from only 1 to 2μg of the samples. Thismethod has been used for the analysis of the samples produced by electromag-netic separator.