NEMI Method Summary

Method Summary Information

Method Number: I-4062 Media: WATER
Revision: Revised 1985
Method Source: U.S. Geological Survey (USGS)
Subcategory: INORGANIC Analytes in this method
Official Name: Arsenic, atomic absorption spectrometric, hydride, automated
Descriptive Name Arsenic, total, water, hydride _AA
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
99034 Byte file
Brief Method
Summary:
 Organic arsenic-containing compounds are decomposed either by sulfuric acid-potassium persulfate digestion or by ultraviolet radiation. The arsenic so liberated, together with inorganic arsenic originally present, is subsequently reduced to arsine with sodium borohydride.
The arsine is stripped from the solution with the aid of nitrogen and is then decomposed in a tube furnace placed in the optical path of an atomic absorption spectrometer.
For additional information on the determination of arsenic in water, see Pierce and others (1976), and Fishman and Spencer (1977).
Scope And
Application:
 This method may be used to analyze water and water-suspended sediment containing at least 1 ug/L of arsenic. Samples containing more than 20 ug/L need to be diluted.
Total arsenic in water-suspended sediment may be determined after each sample has been thoroughly mixed by vigorous shaking and a suitable portion has been rapidly withdrawn from the mixture (NOTE 2).
NOTE 2. Do not use a sample containing more than 1 g/L sediment. Concentrations greater than 1 g/L cause erratic results.
Both inorganic and organic forms of arsenic are determined. To determine only inorganic arsenic, omit the acid-persulfate digestion or the ultraviolet radiation.
Applicable
Conc Range:
 1-20 ug/L
Interferences: Since the arsine is freed from the original sample matrix, interferences are minimized.
A detailed inorganic-interferences study showed that most trace elements at concentration levels of less than 300 ug/L do not interfere (Pierce and Brown, 1976).
QC Requirements: Calibrate instrument using calibration standards (CAL). Quality control samples (QCS) and laboratory blanks (LB) analyzed at a minimum of I each after every 10 samples. (Reference OFR 95-443).
Sample Handling: Container Description: 250 mL Polyethylene bottle, acid-rinsed.
Treatment and Preservation: Use unfiltered sample to rinse bottles, then acidify collected sample with HNO3 to pH < 2.
Max Holding Time:
 180 days
 
Relative Cost: Less than $50
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