Determination of sodium in magnesian and aluminiferous materials by INAA using a thermal column

Several ppm of sodium can be determined in aluminum, alumina and magnesia samples by INAA in which fast neutron interferences are corrected by irradiating the samples in various locations of the thermal column different in fast to thermal neutron flux ratio. A simple INAA using thermal column is effective for sodium determination in geochemical standard reference samples of peridotite and dolomite containing considerable amount of magnesia as one of the matrix elements.