Results of the US Geological Survey's second International Interlaboratory Analytical Comparison Study; Standard Reference Water Samples M-86 (major constituents), T-87 (trace constituents), and P-5 (precipitation snowmelt)

The U.S. Geological Survey began an interlaboratory testing program of standard-reference water samples in 1962. Program objectives have been to provide a means for participating anaytical laboratories to: (1) Identify analytical problems, (2) ascertain the accuracy and precision of common water analyses and analytical methods, and (3) obtain reference samples for continuing quality-assurance testing. Participation in this continuing quality-assurance program is mandatory for all domestic laboratories providing water-analysis data for Survey use and storage in the WATSTORE data-storage system, if appropriate standard-reference water samples are available. The program was expanded in October 1982 to include laboratories in other countries. This report presents analytical data submitted by the 53 laboratories in other countries that analyzed the standard-reference water samples distributed in October 1983. Statistical evaluation of the data and performance ratings achieved by the laboratories for each determination are given in nine tables. Comparisons of the most probable values for the constituents determined by both other countries and domestic laboratories also are presented. (USGS)