NEMI Method Summary

Method Summary Information

Method Number: I-3860 Media: WATER
Revision: 1985
Method Source: U.S. Geological Survey (USGS)
Subcategory: INORGANIC Analytes in this method
Official Name: Turbidity, nephelometric
Descriptive Name Turbidity, nephelometric
Source Info: USGS Branch of Information Services
Box 25286, MS 417
Federal Center
Denver, CO 80225-0286
Phone: 303-202-4700
Citation: USGS Methods, Volume A1
110609 Byte file
Brief Method
Summary:
 The method presented below is based upon a comparison of the intensity of light scattered by the sample under defined conditions with the intensity of light scattered by a standard reference suspension under the same conditions. The greater the intensity of scattered light, the greater the turbidity. Formazin polymer, which has gained acceptance as the turbidity standard reference suspension in the brewing industry, is also used as the turbidity standard reference suspension for water. It is easy to prepare and is more reproducible in its light-scattering properties than is clay or turbid, natural-water standards. The turbidity of a particular concentration of Formazin suspension is defined as 40 NTU. This same suspension of Formazin has a turbidity of approximately 40 units when measured on the Jackson candle turbidimeter; therefore, turbidity units based on the Formazin preparation will closely approximate those derived from the Jackson candle turbidimeter but may not always be identical to them.
For additional information on the turbidity measurement and its significance, see American Public Health Association and others (1980), California State Water Quality Control Board (1963), and U.S. Public Health Service (1962).
Scope And
Application:
 This method is generally applicable to any water that does not contain coarse material that settles rapidly. Samples having greater than 100 nephelometric turbidity units (NTU) must be diluted prior to analysis.
Applicable
Conc Range:
 0.1 to 100 NTU.
Interferences: The presence of colored solutes causes measured turbidity values to be low. Precipitation of dissolved constituents (for example, Fe) causes measured turbidity values to be high.
QC Requirements: Calibrate instrument using calibration standards (CAL); quality control samples (QCS); and laboratory blanks (LB) analyzed at a minimum of 1 for every 10 samples.
Sample Handling: Container Description: 125 mL polyethylene bottle.
Treatment and Handling: Use unfiltered sample to rinse bottle.
Max Holding Time:
 NA
 
Relative Cost: Less than $50
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