Abstract
To address a fundamental need in stable isotope metrology, the National Institute of Standards and Technology (NIST) has established a Web-based interactive data processing system accessible through a common gateway interface (CGI) program on the internet site
http://www.acg.nist.gov/widps-co2. This is the first application of a web-based tool that improves the measurement traceability afforded by a series of NIST standard materials. Specifically, this tool promotes the proper usage of isotope reference materials (RMs) and improve the quality of reported data from extensive measurement networks. Through the International Atomic Energy Agency (IAEA), we have defined standard procedures for stable isotope measurement and data-processing, and have determined and applied consistent reference values for selected NIST and IAEA isotope RMs. Measurement data of samples and RMs are entered into specified fields on the Web-based form. These data are submitted through the CGI on a NIST Web server, where appropriate calculations are performed and results returned to the client. Several International laboratoratories have independently verified the accuracy of the procedures and algorithm for measurements of naturally occurring carbon-13 and oxygen-18 abundances, as well as slightly enriched compositions up to about 150% relative to natural abundances. To conserve the use of the NIST RMs, users are may determine value assignments for secondary standards to be used in a routine basis. Users may also wish to validate proprietary algorithms embedded in their laboratory instrumentation, or specify the values of fundamental variables that are usually fixed in reduction algorithms in order to see the effect upon the calculations. The results returned from the web-based tool are limited in quality only by the measurements themselves, and further value may be realized through the normalization function. When combined with stringent measurement protocols, two- to threefol