USGS-NWQL: I-1800: Strontium, dissolved, atomic absorption spectrometric
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Official Method Name
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Strontium, atomic absorption spectrometric, direct |
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Current Revision
| 1965 |
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Media
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WATER |
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Instrumentation
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Flame Atomic Absorption |
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Method Subcategory
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Inorganic |
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Method Source
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Citation
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Methods for the Determination of Inorganic Substances in Water and Fluvial Sediments, Techniques of Water-Resources Investigations of the United States Geological Survey, Book 5, Chapter A1 Edited by Marvin J. Fishman and Linda C. Friedman |
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Brief Method Summary
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Strontium is determined by atomic absorption spectrometry. Lanthanum chloride and excess potassium chloride are added to mask interferences and control ionization of strontium in the flame (Fishman and Downs, 1966). This procedure may be automated by the addition of a sampler, a proportioning pump, and a strip-chart recorder or a printer or both (fig. 1). |
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Scope and Application
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This method may be used to analyze water containing from 10 to 5,000 ug/L of strontium. Samples containing more than 5,000 ug/L need to be diluted. Samples containing more than 2,500 mg/L of total solutes need first to be diluted. If the strontium concentration in the diluted sample is below detection, the undiluted sample needs to be analyzed by the standard-addition method. |
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Applicable Concentration Range
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10 to 5000 ug/L |
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Interferences
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Sodium and potassium decrease the strontium ionization in the flame. To control the ionization, 1,000 mg/L of potassium are added to both standards and samples. Aluminum, phosphate, and silica interfere but are masked by the addition of lanthanum. Nitrate interferes, but in the presence of lanthanum chloride-potassium chloride solution at least 2,000 mg/L can be tolerated. The addition of nitric acid in the field to preserve samples causes no problem. Low strontium values result even in the presence of potassium and lanthanum if the dissolved-solids concentration exceeds 2,500 mg/L. For this reason, brines and highly mineralized waters must either be diluted or analyzed by the standard-addition method. For the standard-addition method, the dissolved solids content of the samples must be reduced to less than 20,000 mg/L. |
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Quality Control Requirements
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Calibrate instrument using calibration standards (CAL); quality control samples (QCS); and laboratory blanks (LB) analyzed at a minimum of 1 for every 10 samples. |
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Sample Handling
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Container Description: 250 mL polyethylene bottle, nitric acid rinsed Treatment and handling: Filter through 0.45-um filter, use filtered sample to rinse container, acidify sample with nitric acid to pH <2 |
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Maximum Holding Time
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180 days |
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Relative Cost
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Less than $50 |
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Sample Preparation Methods
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