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Illinois Water Science Center Home 		Processing Methods
Once ground water is pumped from the well, through Teflon hose and into the sampling chamber, it is collected in various bottles. Specific types of sample bottles are chosen for each corresponding analyte. These sample bottles range in volume from 60 milliliters to 1.0 liter, depending on the analyte being collected. Unfiltered samples run directly to bottles from the Teflon hose. Different filters are used to collect samples for different analytes. A 0.45 micron silver filter is used to process samples to be analyzed for dissolved organic carbon. Nutrients and trace element samples are filtered through a 0.45 micron Gelman filter. Samples to be analyzed for pesticides pass through a glass fiber, 0.7 micron filter. Solid phase extractions are subsequently performed on pesticide samples within four days of collection. All samples are then shipped to the National Water Quality Laboratory (NWQL) in Denver, CO.

Once the samples arrive at the NWQL, they are separated according to the type of analysis needed to be performed. The Inorganic Chemistry Program at the NWQL receives samples for the determination of metals, major anions and cations, nutrients, and physical properties. The inorganic units within this program which process ground-water samples include trace metals, majors, and nutrients. The Organic Chemistry Program receives samples for the determination of insecticides, herbicides, and industrial organic compounds. The organic units which process ground-water samples include carbon, liquid chromatography, gas chromatography of water, and mass spectrometry of volatiles. Samples are prepared for analysis within 7 working days of receipt at the NWQL. After the analyses are completed, the results are entered into a data base for USGS retrieval.

Personnel to contact about a specific subject are listed on the staff page.
U.S. Department of the Interior
U.S. Geological Survey
221 North Broadway, Urbana, IL 61801, USA
URL: http://il.water.usgs.gov/proj/lirb/gw/process_method/index.html
Maintainer: djfazio@usgs.gov
Last modified: 11:15 CST Thurs 11 May 2000