One of the most important components of an ion mobility spectrometer (IMS) is its ionization source. The common ionization source in IMS is radioactive isotopes 63 Ni. Due to extra regulations, the radioactive source has been replaced with different ionization sources. A widely used alternative ionization source in IMS is corona discharge (CD) source. Proton transfer reaction is the dominant mechanisms in the CD source which make that the best alternative for compounds with high proton affinities. However, in some cases, such as analysis of the bulk samples, very high sensitivity is not required and memory effect may limit the application of CD. Another alternative source of ionization is sodium cation.In this Work, a stable source of sodium ion was developed using thermal ionization of Graphite Intercalation Compounds (GIC). The advantages and shortcomings of the new source in compare with the corona discharge method were evaluated. Unlike in the CD source, the reactant ion peak (RIP) for the sodium ion source was a single peak leaving more room for the product ion peak to be separately appeared. In addition, the RIP is narrower compared to that for CD. Furthermore, the RIP appears in shorter drift times. Unlike in CD source, spectra for selected alkaloids obtained with the sodium ion ionization source show simple pattern including a narrow single peak for each compound with no overlap which reveals an enhanced resolving power. In all cases the product ion peak (PIP) in the sodium ionization source appeared in longer drift times leading to higher peak-to-peak resolution. Finally the sodium ion source was less sensitive to the selected compounds. This can in some cases be a privilege especially in repetitive bulk analysis where fast cleaning is required.