Method 7196A Water

Hexavalent Chromium (Colorimetric)


Method 7196A is used to determine the concentration of dissolved hexavalent chromium [Cr(VI)] in EP/TCLP characteristic extracts and ground waters.  This method may also be applicable to certain domestic and industrial wastes, provided that no interfering substances are present.

The sample is acidified and reacted with diphenylcarbazide.  The resulting red-violent color is measured colorimetrically.  Molybdenum, vanadium, and mercury are known interferences.

The working range of the method is from 0.5 to 50 mg of Cr(VI) per liter.


(EPA SW-846)

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Method Data

Hold Times, Preservatives, Preps, Collection, Analytical & Documentation
Holding Time:   24 hours from sample collection to analysis. The samples should be analyzed as soon as possible after collection.
Preservatives:   Store samples at 4°C from collection until analysis.
Required Preps:   125mL Amber glass or plastic bottle with Teflon-lined lid
Collection Method:   Grab sampling
Analytical Methodology:   Colorimetric
Documentation:   7196A

Analyte List*

Analyte Formula CAS Number Detection Limit
Hexavalent chromium
Cr+6
18540-29-9
50
 mg/L

* The analytes and detection limits listed for each method represent the typical detection limits and analytes reported for that particular method. Keep in mind that analyte lists may vary from laboratory to laboratory. Detection limits may also vary from lab to lab and are dependent upon the sample size, matrix, and any interferences that may be present in the sample.