Trace elements in coal by optical emission spectroscopy

Two quantitative emission spectrochemical methods, direct-reading and photographic, were developed to analyze 16 trace elements in high-temperature coal ash. Problems such as possible loss of vanadium and molybdenum by volatilization and an apparent increase in boron concentration with increasing ashing temperature were encountered in ashing coal samples. Because natural and/or analyzed standards were unavailable, synthetic standards were prepared for the direct-reading method. U.S.G.S. standard granite G-2 and iron oxide were combined with various amounts of a mixture of silica, alumina, and 1000 ppM of each of the trace elements of interest. For the photographic method, similar mixtures were prepared without the G-2 base. For each element, usable concentration limits, concentration ranges on the coal basis calculated from the coal ash samples, and the resulting standard deviations were determined. (U.S.)