NEMI Method Summary

Method Summary Information

Method Number: I-1152 Media: WATER
Revision: Revised 1985
Method Source: U.S. Geological Survey (USGS)
Subcategory: INORGANIC Analytes in this method
Official Name: Calcium, atomic absorption spectrometric, direct
Descriptive Name Calcium, dissolved, water, FLAA
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
23072 Byte file
Brief Method
Summary:
 Calcium is determined by atomic absorption spectrometry (Fishman and Downs, 1966). Lanthanum chloride is added to mask interferences.
This procedure may be automated by the addition of a sampler, a proportioning pump, and a strip-chart recorder or printer or both.
Scope And
Application:
 This method maybe used to analyze atmospheric precipitation, water, brines, and water-suspended sediment.
Two analytical ranges for calcium are included: from 0.01 to 5.0 mg/L and from 1.0 to 60 mg/L. Sample solutions containing calcium concentrations greater than 60 mg/L need to be diluted.
Applicable
Conc Range:
 0.01-5 mg/L
1.0-60 mg/L
Interferences: Phosphate, sulfate, and aluminum interfere but are masked by the addition of lanthanum. Silica also reportedly interferes. Because low calcium values result if the pH of the sample is above 7, standards are prepared in hydrochloric acid solution and samples are preserved in the field with use of nitric acid solution. Concentrations of magnesium greater than 1,000 mg/L also cause low calcium values.
Nitrate interferes, but in the presence of lanthanum chloride-hydrochloric acid solution at least 2,000 mg/L can be tolerated. The addition of nitric acid to the sample causes no problem in the following procedure.
QC Requirements: Update QC requirement field to: 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: Filter through 0.45-um filter, use filtered sample to rinse containers and acidify sample with HNO3 to pH < 2.
Max Holding Time:
 180 days
Sample Prep Met None
Relative Cost: Less than $50
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