Adjustment of pesticide concentrations for temporal changes in analytical recovery, 1992–2010

Data Series 630
National Water-Quality Assessment Program
By:  and 



Recovery is the proportion of a target analyte that is quantified by an analytical method and is a primary indicator of the analytical bias of a measurement. Recovery is measured by analysis of quality-control (QC) water samples that have known amounts of target analytes added ("spiked" QC samples). For pesticides, recovery is the measured amount of pesticide in the spiked QC sample expressed as a percentage of the amount spiked, ideally 100 percent. Temporal changes in recovery have the potential to adversely affect time-trend analysis of pesticide concentrations by introducing trends in apparent environmental concentrations that are caused by trends in performance of the analytical method rather than by trends in pesticide use or other environmental conditions. This report presents data and models related to the recovery of 44 pesticides and 8 pesticide degradates (hereafter referred to as "pesticides") that were selected for a national analysis of time trends in pesticide concentrations in streams. Water samples were analyzed for these pesticides from 1992 through 2010 by gas chromatography/mass spectrometry. Recovery was measured by analysis of pesticide-spiked QC water samples. Models of recovery, based on robust, locally weighted scatterplot smooths (lowess smooths) of matrix spikes, were developed separately for groundwater and stream-water samples. The models of recovery can be used to adjust concentrations of pesticides measured in groundwater or stream-water samples to 100 percent recovery to compensate for temporal changes in the performance (bias) of the analytical method.
Publication type Report
Publication Subtype USGS Numbered Series
Title Adjustment of pesticide concentrations for temporal changes in analytical recovery, 1992–2010
Series title Data Series
Series number 630
DOI 10.3133/ds630
Year Published 2011
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) National Water Quality Assessment Program, Pesticide National Synthesis Project
Description vi, 11 p.; PDF Download of Appendix 3; PDF Download of Appendix 3 List of Figures; PDF Download of Appendix 1 Metadata; PDF Download of Appendix 2 Metadata; PDF Download of Appendix 4 Metadata; PDF Download of Appendix 5 Metadata; Download of Appendixes 1, 2, 4, and 5
First page i
Last page 11
Time Range Start 1992-01-01
Time Range End 2010-12-31
Additional Online Files (Y/N) Y
Google Analytic Metrics Metrics page
Additional publication details