Publications

This report describes the equipment and procedures used for on-site filtration of surface-water and ground-water samples for determination of organic compounds. Glass-fiber filters and a positive displacement pumping system are suitable for processing most samples for organic analyses. An optional system that uses disposable in-line membrane filters is suitable for a specific gas...

This report is a compilation of analytical results from a study conducted at the U.S. Geological Survey, National Water Quality Laboratory (NWQL) in 1992 to assess the effectiveness of three field treatment protocols to stabilize nutrient concentra- tions in water samples stored for about 1 month at 4C. Field treatments tested were chilling, adjusting sample pH to less than 2 with...

A method for the determination of 30 individual organochlorine pesticides, total toxaphene, and total polychlorinated biphenyls (PCBs) in bottom sediment is described. The method isolates the pesticides and PCBs by solvent extraction with dichlorobenzene, removes inorganic sulfur, large naturally occurring molecules, and other unwanted interferences by gel permeation chromatography, and...

Quality-control practices are established for the operation of the U.S. Geological Survey's National Water Quality Laboratory. These practices specify how samples are preserved, shipped, and analyzed in the Laboratory. This manual documents the practices that are currently (1995) used in the Laboratory.

A method has been developed to measure nanogram per liter amounts of selected volatile organic compounds (VOCs) including dichlorodifluoromethane, trichlorofluoromethane, cis-1,2-dichloroethene, trichloroethene, tetrachloroethene, and the isomers of dichlorobenzene in water. The method uses purge-and-trap techniques on a 100 mL sample, gas chromatography with a megabore capillary column...

No abstract available.

In an intensive subcontimental study of pesticides in surface waters of the United States, concentrations of 26 high-use pesticides were measured at nine sites in the Mississippi River basin from May 1991 through March 1992. Calculated total fluxes were combined with agricultural-use data to estimate the percentage of applied pesticide reaching the mouths of the Mississippi River and six...

Methyl tert-butyl ether (MTBE) was found in shallow ground-water samples in a study of 8 urban and 20 agricultural areas throughout the United States in 1993 and 1994 (Squillace and others, 1995, p. 1). The compound is added to gasoline either seasonally or year round in many parts of the United States to increase the octane level and to reduce carbon monoxide and ozone levels in the air...

This Services Catalog contains information about field supplies and analytical services available from the National Water Quality Laboratory in Denver, Colo., and field supplies available from the Quality Water Service Unit in Ocala, Fla., to members of the U.S. Geological Survey. To assist personnel in the selection of analytical services, this catalog lists sample volume, required...

A method for the determination of chlorinated organic compounds in aquatic tissue by dual capillary-column gas chromatography with electron-capture detection is described. Whole-body-fish or corbicula tissue is homogenized, Soxhlet extracted, lipid removed by gel permeation chromatography, and fractionated using alumina/silica adsorption chromatography. The extracts are analyzed by...

A method for the determination of methylene blue active substances in whole-water samples by liquid-liquid extraction and spectrophotometric detection is described. Sulfate and sulfonate-based surfectants are reacted with methylene blue to form a blue-colored complex. The complex is extracted into chloroform, back-washed with an acidified phosphate-based buffer solution, and measured...

The National Water Quality Laboratory (NWQL) offers a variety of analytical services for the determination of constituents in samples of water, sediment, and biological material. As technology has advanced, many new methods have been introduced but not always incorporated into plans and schedules developed in the districts. The strengths and weaknesses of many different techniques are...