A solution-based inductively coupled plasma optical emission spectrometric (ICP-OES) method is described for elemental analysis with relative expanded uncertainties on the order of 0.1% relative. The single-element determinations of 64 different elements are presented, with aggregate performance results for the method and parameters for the determination of each element. The performance observed is superior to that previously reported for ICP-OES, resulting from a suite of technical strategies that exploit the strengths of contemporary spectrometers, address measurement and sample handling noise sources, and permit rugged operation with small uncertainty. Taken together, these strategies constitute high-performance ICP-OES.

A gravimetric method for the determination of sulfate in a sulfate solution standard by the precipitation of barium sulfate is coupled with the instrumental determination of trace sulfate and precipitate contaminants to improve the accuracy and precision of the analysis. Sulfate in a solution of potassium sulfate is separated by a reverse precipitation with barium chloride in very dilute hydrochloric acid. Coulometry, ICP-MS, and flame atomic emission spectrometry (FAES) are used to quantify the level of the contamination in the barium sulfate precipitate and the solubility loss of sulfate in the filtrate, from which correction factors are calculated.Coprecipitating contaminants contribute about 0.3% to the total precipitate mass, while the analyte lost to the filtrate contributes 0.4%. Despite the poorer precision and accuracy of instrumental methods, the over-all precision and accuracy of the sulfate determination is actually improved, since the instrumental methods are used to determine only a very small part of the analyte. The expanded uncertainty (k = 2) of the method is below 0.2% relative to the precipitate mass.

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Standard reference material (SRM) 2584 (Trace Elements in Indoor Dust) was developed as a reference standard for evaluating field methods and for validating laboratory and reference methods for the assessment of lead contamination and exposure. In addition to lead, the toxic trace elements As, Cd, Cr, and Hg, at approximately 17, 10, 140, and 5 microg g(-1), respectively, have been certified in the SRM. These four analytes were successfully determined by use of high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). Isobaric interferences at masses of As and Cr were resolved by using the high resolution mode (nominal 8000) and the medium resolution mode (nominal 3000), respectively, of the instrument. The effects of a significant drift in analyte sensitivity in the course of measurement were rectified by use of internal standardization, single spike standard addition, and an optimized analysis sequence. The results were compared with those obtained by instrumental neutron activation analysis (INAA) and isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS). The results for the quality control, SRM 2704 (Buffalo River Sediment), were in good agreement with the certified values, indicated by the uncertainty intervals of the measured values overlapping the certified intervals at 95% confidence level.