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Open-File Report 97–223

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National Water-Quality Assessment Program

Quality-Control Design for Surface-Water Sampling in the National Water-Quality Assessment Program

By David K. Mueller, Jeffrey D. Martin, and Thomas J. Lopes

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The data-quality objectives of the National Water-Quality Assessment Program include estimating the extent to which contamination, matrix effects, and measurement variability affect interpretation of chemical analyses of surface-water samples. The quality-control samples used to make these estimates include field blanks, field matrix spikes, and replicates. This report describes the design for collection of these quality-control samples in National Water-Quality Assessment Program studies and the data management needed to properly identify these samples in the U.S. Geological Survey's national data base.





Purpose and Scope


Types of Quality-Control Samples

Collection and Processing of Quality-Control Samples

Field Blanks

Inorganic Constituents and Pesticides

Dissolved and Suspended Organic Carbon

Volatile Organic Compounds

Trip Blanks

Field Matrix Spikes


Volatile Organic Compounds

Spike Recovery Calculations


Inorganic Constituents, Pesticides, and Suspended Sediment

Dissolved and Suspended Organic Carbon

Volatile Organic Compounds

Frequency, Timing, and Location of Quality-Control Sample Collection

Data Management


Appendix A—Constituents Included in National Water Quality Laboratory Schedules and Codes Referred to in this Report

Appendix B—Analytical Services Request and National Water Information System Data-Base Coding Required for Quality-Control Samples and Associated Environmental Samples Collected as Part of the National Water-Quality Assessment Program


Environmental Sample Associated with the Blank

Field Blank

Canister Blank

Trip Blank


Primary Environmental Sample Associated with the Spikes

Duplicate Environmental Sample Associated with the Spikes

Field Matrix Spike

Field Matrix Spike Duplicate


Primary Environmental Sample

Duplicate Environmental Sample

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A full listing of NAWQA activities is available at: logo