Thomas is an inorganic analytical chemist. During his first few years at NIST he determined gases in metals by combustion and IR detection and multiple elements in metals by spark emission spectrometry. Since 1984 he has been using gravimetric separations, coupled with instrumental detection of residual analyte and precipitate contaminants and also titrimetry for "high-accuracy" (U = 0.03% to 0.3%) elemental determinations. During this time he has also been active in using microwave-oven digestion for sample preparation. He has performed sample preparation and spiking to support isotope dilution mass spectrometry. For more than 15 years, he has promoted the quantification of measurement uncertainty to improve measurement quality. This promotion has included chairing ACS national meeting symposiums on "Quantification of Measurement Uncertainty" and invited presentations on his simple step-wise approach to uncertainty quantification that uses numerical differentiation in a Kragten spreadsheet to propagate uncertainty. Along with William Guthrie, a NIST mathematical statistician, he is working on co-editing a book on practical applications of the quantification of measurement uncertainty in analytical chemistry. He is the technical project leader (TPL) for solid fuel (coal and coke) SRMs and anion SRMs.
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