USGS-NWQL: I-1232: Chromium, hexavalent, dissolved, water, FLAA
|
Official Method Name
|
Chromium, hexavalent, atomic absorption spectrometric, chelation-extraction |
|---|---|
|
Current Revision
| Revised 1985 |
|
Media
|
WATER |
|
Instrumentation
|
Flame Atomic Absorption |
|
Method Subcategory
|
Inorganic |
|
Method Source
|
|
|
Citation
|
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 |
|
Brief Method Summary
|
Hexavalent chromium is determined by atomic absorption spectrometry. The element is chelated with ammonium pyrrolidine dithio-carbamate (APDC) and extracted with methyl isobutyl ketone (MIBK). The extract is aspirated into the air-acetylene flame of the spectrometer (Midgett and Fishman, 1967). |
|
Scope and Application
|
This method may be used to analyze water and brines containing from 1 to 25 ug/L of chromium. Samples containing more than 25 ug/L need to be diluted prior to chelation-extraction. If the iron concentration of the sample exceeds 5,000 ug/L, determine hexavalent chromium by the colorimetric diphenylcarbazide method (I-1230). |
|
Applicable Concentration Range
|
1- 25 ug/L |
|
Interferences
|
Concentrations of iron greater than 5,000 ug/L interfere by suppressing the chromium absorption. |
|
Quality Control 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: Filter through 0.45-um filter, use filtered sample to rinse containers and acidify sample with HNO3 to pH < 2. |
|
Maximum Holding Time
|
180 days |
|
Relative Cost
|
Less than $50 |
|
Sample Preparation Methods
|
