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H.N. Elsheimer

Publications and source records attributed to H.N. Elsheimer.

8 recordsLinked to original sources
USGS1993

Optimization of an extraction procedure for the accurate determination of total tin in eighteen Geological Survey of Japan rock reference materials

A fusion-extraction procedure for the determination of total tin in rocks and sediments by graphite furnace atomic absorption spectrometry (GFAAS) was reexamined and modified to obtain the optimum accuracy and precision. Several variations based on increases in the sample weight or extraction ratio were compared based on the determination of tin in 18 Geological Survey of Japan (GSJ) reference materials. The most accurate and precise procedure was found to be an 8:1 extraction of a 0.5 g rock sample fused with lithium metaborate and dissolved in 7.5% hydrochloric acid, using a 4% solution of trioctylphosphine oxide in methyl isobutyl ketone (TOPO-MIBK). Rocks containing <I ug/g total tin require a 0.5 g sample size for the utmost accuracy. Utilizing these modifications, tin concentrations were found to be within 0.1 ug/g for all of the GSJ reference standards with the exception of the rhyolites. Values are reported for the total tin content of three new GSJ reference materials, namely, JLk-1, JLs-1, and JDo-1.

Analytical Sciences↗
USGS1990

Determination of total tin in silicate rocks by graphite furnace atomic absorption spectrometry

A method is described for the determination of total tin in silicate rocks utilizing a graphite furnace atomic absorption spectrometer with a stabilized-temperature platform furnace and Zeeman-effect background correction. The sample is decomposed by lithium metaborate fusion (3 + 1) in graphite crucibles with the melt being dissolved in 7.5% hydrochloric acid. Tin extractions (4 + 1 or 8 + 1) are executed on portions of the acid solutions using a 4% solution of tricotylphosphine oxide in methyl isobutyl ketone (MIBK). Ascorbic acid is added as a reducing agent prior to extraction. A solution of diammonium hydrogenphosphate and magnesium nitrate is used as a matrix modifier in the graphite furnace determination. The limit of detection is > 10 pg, equivalent to > 1 ??g l-1 of tin in the MIBK solution or 0.2-0.3 ??g g-61 in the rock. The concentration range is linear between 2.5 and 500 ??g l-1 tin in solution. The precision, measured as relative standard deviation, is < 20% at the 2.5 ??g l-1 level and < 7% at the 10-30 ??g l-1 level of tin. Excellent agreement with recommended literature values was found when the method was applied to the international silicate rock standards BCR-1, PCC-1, GSP-1, AGV-1, STM-1, JGb-1 and Mica-Fe. Application was made to the determination of tin in geological core samples with total tin concentrations of the order of 1 ??g g-1 or less.

Analytica Chimica Acta↗
USGS1972

Microcoulometric measurement of water in minerals

A DuPont Moisture Analyzer is used in a microcoulometric method for determining water in minerals. Certain modifications, which include the heating of the sample outside the instrument, protect the system from acid gases and insure the conversion of all hydrogen to water vapor. Moisture analyzer data are compared to concurrent data obtained by a modified Penfield method. In general, there is a positive bias of from 0.1 to 0.2% in the moisture analyzer results and a similarity of bias in minerals of the same kind. Inhomogeneity, sample size, and moisture pick-up are invoked to explain deviations. The method is particularly applicable to small samples.

Analytica Chimica Acta↗
USGS1967

Complexometric determination of gallium with calcein blue as indicator

A metalfluorechromic indicator, Calcein Blue, has been used for the back-titration of milligram amounts of EDTA in presence of gallium complexes. The indicator was used in conjunction with an ultraviolet titration assembly equipped with a cadmium sulphide detector cell and a microammeter for enhanced end-point detection. The result is a convenient and rapid method with an accuracy approaching 0.1 % and a relative standard deviation of about 0.4% for 10 mg of gallium.

Talanta↗