Abstract
Four different Kansas shales, varying in coloration from a black (reduced) to a red (oxidized), were analyzed for several metal concentrations by flame atomic emission (FAE), flame atomic absorption (FAA), and inductively coupled plasma atomic emission (ICP). Shale samples analyzed by FAE and FAA were subjected to pretreatments including addition of releasing agents and extraction techniques because, as expected, measurements of trace metal concentrations without pretreatment resulted in significant errors. Chemical interferences in the analysis of shales by atomic spectroscopic techniques are severe due to high concentrations of Si, Al, Ca, Mg, and Fe. Organic matter, the presence of S and P, and enrichment in various minor and trace element species may also complicate the analysis of shales derived from reducing environments. However, flame results for pretreated samples show good agreement with ICP determinations on untreated samples. Among the shales investigated, those having higher organic content (black) were found to have higher concentrations of certain metals such as Cr, V, Zn, Cu, Ni, Pb, Mo, and Hg. This is related to the capability of the organic fractions of these shales to concentrate metals.
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