Major and minor oxide and trace element determination in silicate rocks by direct current plasma optical emission echelle spectrometry

Abstract

A technique for the determination of major concentrations of SiOz, AI,O,, Fe203, MgO, CaO, Na,O, and K,O, minor levels of Ti O,, P,O,, and MnO, and trace concentrations of Ba, Cr,Cu, Ni, Sr, V, and Zn, in semi-microsamples (200 mg) of powdered whole rock, is described. Chemically diverse standard reference rocks are used both for calibration and assessment of accuracy. A lithium metaborate fusion melt of each standard or sample is dissolved in dilute HNO, containing CS+ at a level of 0.2% (w/v). The resulting solution is used to perform all analyses except those for NapO and K20, which are determined in a portion of the original sample solution wherein the Cs' concentration has been raised to 0.32% (w/v). Analyses of both portions of each sample solution are performed using an optical emission spectrometerhpectrograph equipped with an echelle monochromator and a dc argon plasma excitation source. Trace element detection limits ranged from 2 ppm for Cu to 15 ppm for Zn. A study of precision based on replicate determinations in three splits of the proposed USGS reference basalt BHVO-1 yielded the following results: (1) For analyses of the major and minor oxide constituents, values of the percent relative standard deviation (RSD) ranged from 1 for CaO, to 21 for P,O,. (2) For trace element determinations, values of the RSD ranged from 2 for Cu, to 19 for Zn.Instrumental determinations of the bulk oxide and trace element compositions of silicate rocks of various types are commonly beset by several problems. It often happens that many analyses must be made of each sample unknown, of which only a smail amount is available, and that several of the trace elements are present a t concentrations in the low ppm range. Moreover, since any specimen of rock is a more or less heterogeneous mixture, the representativeness of its analyzed subsample can legitimately be questioned. In addition, the great complexity and variability of the major and minor element constituencies of silicate rocks engender matrix effects.Since 1970, X-ray fluorescence (XRFs) and atomic absorption spectrometry (AAS) have provided the instrumental techniques most widely employed for the analyses of metals and metalloids in geological materials (1,Z). The use of XRFs for this purpose, however, has two principal disadvantages: it is unsuitable for the determination of any trace element for which 2 < io, and, for routine bulk analysis ( S O 2 , Al2O3.FeLO,, MgO. CaO, Na70, K@, TiOL, P205, and MnO) and /or

Lithology, mineralogy, and geochemistry of the lower ocean crust, ODP Hole 735B, Southwest Indian Ridge

“…The fused glass was then dissolved in dilute nitric acid. The concentrations of the elements Si, Al, Ti, Fe, Mg, Ca, and P were measured using a direct-current plasma atomic emission spectrometer (DCP-AES) (Bankston et al, 1979). The alkali elements Na and K were analyzed by flame atomization atomic absorption spectrometry (AAS).…”

An Evaluation of Methods for the Chemical Decomposition of Geological Materials for Trace Element Determination using ICP‐MS

“…These include open and closed vessel acid digestion methods (Moselhy et al 1978, McQuaker et al 1979, Lechler et al 1980, Church 1981, Uchida et al 1980, McLaren et al 1981, Hee and Boyle 1988, Karstensen and Lund 1989, Jarvis 1990, Boer et al 1993, Dulski 1994, Münker 1998, Liang et al 2000, microwave dissolution (Lamothe et al 1986, Borman 1988, Kingston and Jassie 1988, Mathes 1988, Matusiewicz and Sturgeon 1989, Kemp and Brown 1990, Nölter et al 1990, Totland et al 1995, Yoshida et al 1996, Na 2 O 2 sintering (Robinson et al 1986, Longerich et al 1990) and fusions with alkali fluxes such as LiBO 2 , Li 2 B 4 O 7 , Na 2 O 2 etc. (Burman et al 1978, Bankston et al 1979, Walsh and Howie 1980, Brenner et al 1980, Jarvis 1990). Totland et al (1992) evaluated results from open vessel acid digestion, LiBO 2 fusion, and microwave-heated sealed-vessel acid digestion for thirty eight elements by ICP-MS analysis in nine geological reference materials of varied composition.…”

Mineralization, alteration, and hydrothermal metamorphism of the ophiolite‐hosted Turner‐Albright sulfide deposit, southwestern Oregon

“…Samples were ground in an agate mill to < 100 ttm, dried at 110øC, and fused with LiBO 2 at 950øC for approximately 15 min. Fused powders were dissolved in HC1 and citric acid and diluted 1: 10,000 (H20) and 1:250 (H20) for major and minor element analysis, respectively, using dc-plasma atomic emission spectrometry [Bankston et al, 1979]. Replicate analyses indicate uncertainties of approximately 1-2% of reported values for major and minor elements and 1-10% for trace elements.…”