title: Effect of valence state on ICP-OES value assignment of SRM 3103a arsenic spectrometric solution.
abstract: The certification of Standard Reference Material (SRM is a registered trademark of NIST) 3103a As Spectrometric Solution is based on the gravimetric preparation value that is verified by inductively coupled plasma optical emission spectrometry (ICP-OES) measurements. A disagreement between the gravimetric and the spectrometric values for a batch of As calibration solutions led to the discovery that the solutions contained a mixture of trivalent and pentavalent As species and that the pentavalent species was approximately 8% more sensitive than the trivalent species with ICP-OES determination. The kinetics of the reaction between As metal and nitric acid were studied, and the results were applied to develop a procedure that would consistently produce single-species pentavalent As standards, which eliminates As speciation as a source of measurement bias in the SRM certification process.
authors.affiliation: Analytical Chemistry Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8391, USA. lee.yu@nist.gov
authors.forename: Lee L
authors.initials: LL
authors.lastname: Yu
authors.forename: Therese A
authors.initials: TA
authors.lastname: Butler
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Turk