Interlaboratory comparison of different analytical techniques for the determination of oxygen-18 abundance

• Published in: Analytical chemistry (Washington) Vol. 62; no. 7; pp. 703 - 708
• Main Authors: Speakman, J. R, Nagy, K. A, Masman, D, Mook, W. G, Poppitt, S. D, Strathearn, G. E, Racey, P. A
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.04.1990
• Subjects: 400101 - Activation, Nuclear Reaction, Radiometric & Radiochemical Procedures; Analytical chemistry; CALCULATION METHODS; CHEMICAL ANALYSIS; Chemistry; EVEN-EVEN NUCLEI; Exact sciences and technology; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; INTERLABORATORY COMPARISONS; ISOTOPE RATIO; ISOTOPES; LIGHT NUCLEI; MASS SPECTROSCOPY; NUCLEI; OXYGEN 18; OXYGEN ISOTOPES; QUANTITATIVE CHEMICAL ANALYSIS; RADIOACTIVATION; Spectrometric and optical methods; SPECTROSCOPY; STABLE ISOTOPES; Trace analysis; Water; Oxygen Isotopes; Proton activation; Chemical analysis; Gaseous state; Analytical method; Mass spectrometry; Comparative study
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac00206a011

A series of six artificially enriched waters, containing between 2,500 and 6,500 ppm oxygen-18, was prepared by adding weighed portions of distilled water and highly enriched H{sub 2}{sup 18}O. These waters were analyzed by radio activation analysis (proton activation PAA) and by gas isotope ratio mass spectrometry (gIRMS) with CO{sub 2} as the analysis gas. Carbon dioxide was prepared from water samples either by using the guanidine reaction, with 3-, 5- and 10-{mu}L samples, or by isotopic equilibration, using small (10 {mu}L) and large (1.5 mL) samples. The large samples were diluted to the natural abundance range prior to analysis as were the 3-{mu}L guanidine samples. Precision was greatest with large sample CO{sub 2} equilibration (mean relative standard deviation (RSD) = 0.108%). The other gIRMS gas preparation techniques had lower precision (3 {mu}L guanidine, RSD = 0.529%, 5 {mu}L guanidine, RSD = 0.364%, 10 {mu}L guanidine, RSD = 0.48%; 10 {mu}L equilibration, RSD = 0.43%) and the lowest precision occurred with PAA (RSD = 0.58%). For all the techniques except small sample equilibration, accuracy (percent deviation of mean evaluation from expected gravimetric mean) was worse than precision (RSD).