Isotope ratio measurements of trace Nd by the total evaporation normalization (TEN) method in thermal ionization mass spectrometry

Isotope ratios of very small Nd samples (0.1-5 ng) are measured by the total evaporation normalization (TEN) method. Samples as small as 0.5 ng can be measured with an external precision of 140 ppm by this method. The average Nd-143/Nd-144 ratio of the samples with the measured electric charge Q (Nd-143) = 10-50 x 10(-11) corresponds roughly to 0.5 ng JNdi-1, is 0.51214 +/- 0.00007 (n = 7) and is coherent with the values obtained by conventional dynamic multi-collection thermal ionization mass spectrometric measurements. The precision of 0.5 ng Nd measurements is sufficient for the application of the Nd-143/Nd-144 ratio as a geochemical tracer. The precision of TEN measurements for samples smaller than 5 ng is superior to that of the conventional method. (C) 2007 Elsevier B. V. All rights reserved.