Evaluation of concentration data in geochemical reference materials
Por:
Velasco-Tapia F., Guevara M., Verma S.P.
Publicada:
1 ene 2001
Resumen:
The present study describes the different approaches to process Geochemical Reference Material (GRM) databases and the application of an scheme involving fourteen statistical tests to establish concentration data in five GRMs from the U.S. Geological Survey (basalt BHVO-1, andesite AGV-1, rhyolite RGM-1, and diabases W-1 and W-2). These tests include deviation/spread, Grubbs-type, Dixon-type, and high-order moment statistics. For about 50% of the cases, final mean values are more reliable (characterized by smaller standard deviations) than those obtained earlier using the inadequate "two standard deviation" method. Although about 53% of present mean data are identical (within 1%) to those reported previously, a disagreement > 1 to 5% is observed in 32% of the cases. The remaining mean values show larger differences (20-50%) compared to the literature data. The present procedure of outlier detection and elimination is therefore recommended in the study of GRMs, instead of the probably erroneous "two standard deviation" method. Use of geochemical criteria indicates that the new mean values in basalt BHVO-1 might be closer to the "true" concentrations.
Filiaciones:
Velasco-Tapia F.:
Centro Investigacion Energía, UNAM, Privada Xochicalco s/n, Temixco, Mor. 62580, Mexico
Guevara M.:
Centro Investigacion Energía, UNAM, Privada Xochicalco s/n, Temixco, Mor. 62580, Mexico
Verma S.P.:
Centro Investigacion Energía, UNAM, Privada Xochicalco s/n, Temixco, Mor. 62580, Mexico
|