Mass spectrometric measurements of copper isotopic ratios using low-temperature thermal ionization

Thermal ionization mass spectrometry (TIMS) of Cu isotopes exp 63 Cu and exp 65 Cu has been attained at a low temperature ( approx 900 deg C) in spite of the high ionization potential of Cu. The time variations and the errors of the observed Cu isotopic ratios in this measuring method were much smaller than those of the high-temperature ionization method previously reported. The isotopic analysis for the NBS Cu standard sample obtained by using this method of low-temperature TIMS shows that the observed values are in direct accord with the certified isotopic value without use of a correction factor for the absolute value. For measurements with low-temperature TIMS, copper(II) nitrate samples can be used without special pretreatments. 10 ref.--AA