Analytical Methods

• There are several methods for determining the presence and concentration of hexavalent chromium in soil. All methods first require an extraction, using an alkaline solution such as sodium carbonate and sodium hydroxide, by which the chromium within the soil is released and suspended into an aqueous solution. The extraction process involves adding chemicals to the soil sample and applying heat. The chromium is released from the soil and dissolved into the liquid, which is then removed from the sample and analyzed.
  
  Other chemicals in the soil sample can potentially interfere with the later analysis, and other analyses may be required to determine which, if any, interfering chemicals are confounding the results. The extracted liquid may need further chemical additions depending on which method and/or instrument is going to be used for the determination. For example, one method requires that the trivalent form of chromium first be removed from the solution. The hexavalent chromium is then converted to trivalent chromium and determined using flame or furnace atomic absorption spectroscopy.
  
  Other methods include the use of an ion chromatograph, in which the amount of hexavalent chromium ions corresponds to a "signal" detected by the instrument.
  
  

Chromate in the Environment

• Chromate compounds are used in coloring agents such as paints and inks, and are used as decorative and protective surfaces. According to the Occupational Safety and Health Administration (OSHA), inhalation of hexavalent chromium can lead to irritation of the nose, throat and lungs, and can also result in lung cancer. Continuous exposure has been linked to permanent eye damage, ulcers in the throat, perforated septa and skin ulcers. Because it is a carcinogen, and has been correlated to many other adverse health effects, it is important to have reliable ways to detect the presence of hexavalent chromium in the environment.