USGS-NWQL: I-2243: Cobalt, dissolved, water, GFAA
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Official Method Name
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Cobalt, atomic absorption spectrophotometry, graphite furnace |
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Current Revision
| Revised 1989 |
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Media
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WATER |
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Instrumentation
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Graphite Furnace-Atomic Absorption Spectrometer |
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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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Brief Method Summary
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Cobalt is determined by atomic absorption spectrophotometry in conjunction with a graphite furnace containing a graphite platform (Hinderberger and others, 1981). A sample is placed on the graphite platform, and the sample then is evaporated to dryness, charred, and atomized using high-temperature ramping. The absorption signal produced during atomization is recorded and compared with standards. |
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Scope and Application
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This method is used to determine cobalt in samples of water and water-suspended sediment with a specific conductance not greater than 10,000 uS/cm. With Zeeman background correction and a 20-uL sample, the method is applicable in the range from 1 to 25 ug/L. Sample solutions that contain cobalt concentrations greater than 25 ug/L must be diluted or be analyzed by an alternate method. This method was implemented in the National Water Quality Laboratory in May 1989. |
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Applicable Concentration Range
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1-25 ug/L |
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Interferences
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Interferences for samples with specific conductances less than 10,000 uS/cm normally are small. In addition, the use of the graphite platform reduces the effects of many interferences. Special precautionary measures to prevent contamination need to be used during sample collection and laboratory determination. |
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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 I each after every 10 samples. (Reference OFR 95-443). |
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Sample Handling
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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. |
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Maximum Holding Time
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180 days |
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Relative Cost
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$51 to $200 |
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Sample Preparation Methods
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