Geology topics
Publications and source records attributed to Philip Aruscavage.
Platinum, palladium and rhodium have been determined in 18 U.S. Geological Survey reference materials by graphite furnace atomic absorption spectrometry after preconcentration by the classical leadfree assay technique. A comparison with literature values shows clearly the need for additional data on these samples before “best” values can be assigned.
Tungsten is determined in 11 USGS standard rocks by a spectrophotometric procedure that measures the absorbance of the tungsten-dithiol complex. The results are compared with those obtained by other methods. After the samples are dissolved in HClO 4 and HF, the tungsten-dithiol complex is extracted into isoamyl acetate and then back-extracted into isoamyl acetate. The determination of 0.1 part per million in a 500-mg sample can be made routinely.
Submicrogram quantities of antimony, arsenic, and selenium in coal samples are determined by an atomic absorption procedure using an electrically heated graphite atomizer. The samples are decomposed in a mixture of nitric, sulfuric, and perchloric acids and are separated and concentrated by extraction from sulfuric acid-iodide solution into toluene. The results obtained on several intralaboratory reference samples and the National Bureau of Standards coal 1632 are compared with results from other methods. The determination can be made routinely for concentrations as small as 0.1 parts per million for arsenic, antimony, and selenium in the coal.
A rapid procedure is described for the determination of lead in rocks by an isotope-dilution substoichiometric method. After the sample has been digested with acid in the presence of 210 Pb tracer, the lead is separated by dithizone extractions. After the lead has been back-extracted into aqueous solution, it is reacted with a substoichiometric amount of EDTA. Excess of unreacted lead is removed by extraction with dithizone in carbon tetrachloride, and the specific activity of the aqueous complex is determined by counting 210 Pb. The standard deviation of the method is less than 10 % for replicate determinations of lead in several U.S. Geological Survey standard rocks. The agreement with literature values indicates that the method is accurate.