Three different methods have been examined to express the densities of spectrograms recorded on an Ilford Q2plate in our Mattauch-Herzog type mass spectrograph. The exposures have been decided by the integrated ion currents measured by the monitor electrode, thus their fluctuations have been eliminated without any internal standard. As examples, the isotopic abundances of Cu and Zn have been measured with appropriate calibration curves . The precision and accuracy of the measurements have been briefly discussed.
