Quality-assurance data for routine water analysis in the laboratories of the US Geological Survey for water-year 1983

The U.S. Geological Survey maintains a quality-assurance program based on the analysis of reference samples for its two water-analysis laboratories located in Atlanta, Georgia, and Denver, Colorado. Reference samples containing selected inorganic constituents are prepared at the U.S. Geological Survey 's Ocala, Florida office and disguised as routine samples , and sent daily or weekly, as appropriate, to each laboratory through other U.S. Geological Survey offices. The results are permanently stored in the National Water Data Storage and Retrieval System (WATSTORE), the U.S. Geological Survey 's data base for all water data. These data are analyzed statistically for precision, bias, and comparability. The results of these statistical analyses are presented for data collected during the 1983 water year. Nutrient samples, simulated precipitation (low-concentration level) samples and selected pesticide samples were also submitted as samples of unknown concentrations. The results of these determinations were statistically analyzed for comparability and these data are presented. In addition, a summary of recovery and precision data from three different instruments for volatile organics is presented. (USGS)