Analyse des Standards de L'U.S.G.S. : GXR‐1 a GXR‐6 par Activation Neutronique et Fluorescence X

Abstract

Six roches standards de I'USGS : GXR‐1 à GXR‐6 ont été analysées par activation neutronique instrumentale (INAA) pour le dosage de 17 éléments traces et par fluorescence X (XRF) pour les autres éléments difficiles à doser par activation neutronique. Les travaux précédemment publiés par Gladney et al. ont été pris comme référence en particulier les valeurs recommandées (R.V.) qui sont généralement en bon accord avec nos résultats. Quelques remarques et corrections sont proposées pour expliquer certaines disparités. Six United States Geological Survey's (USGS) Geochemical Exploration References Samples (GXR) have been analyzed by instrumental neutron activation analysis (INAA) for the determination of seventeen trace elements and by X‐ray fluorescence spectrometry (XRFS) for other trace elements difficult to determine by INAA. Our results compare favourably with the values recommended by E.S. Gladney et al. Some suggestions and corrections are proposed to explain some discrepancies.

Analysis of Standard Reference Materials for Zr, Nb, Hf and Ta by ICP‐MS after Lithium Metaborate Fusion and Cupferron Separation*

“…All results by this method fall within the standard deviations given for consensus values. Results for Zr in the GXR series agree with those obtained using XRF by Meyer et al (19) with the exception of the jasperoid GXR-1 where this value of 28 ppm is closer t3 that of Watkins arid Thompson (1 2), 30 pprn by ICP-ES and LBO2 fusion. 'The lack of agreement for Zr in MESS-1 and BCSS-1 is not cause for concern as the concentrations cited are semi-quantitative only and intended as guideline information.…”

“…The results of the application of the proposed method to the determination of Zr, Nb, H f and Ta in 74 geological SRMs are shown in Tables 1 and 2. The literature values given for comparison purposes are derived from compilation reports (6,(16)(17)(18)20,23,25,27), certificate information (21.22) and individual methods (1,19,26,28). Values which are underlined are 'recommended' as distinguished from 'proposed' and are taken from the recent major international compilation by Govindaraju (16).…”

“…0.46 5.6 1.79 f 0.07 3.9 (n-9) (n = 71 reported to date and their number (in brackets, following), as supplied by Gladney (6). The reader should note that the standard deviations shown for H f and Ta in the GXR series (19) and for all analytes in the GSJ series (26) relate to the errors inherent in the particular application of individual methods, i.e., lNAA for Hf and Tit and fused disc WD-XRF for Z r and Nb. The replicate artalyses shown in Table 3 for SY-2, SY-3, PACS-1, MESS-1 and GL-0 demonstrate the precision of the proposed method for all four analytes.…”