Facts about the ASTM D3921 Standard Test Method
The ASTM D3921 is a standard test method for Oil and Grease and Petroleum Hydrocarbons in Water. Its importance is based on unique advantages such as accuracy, short measurement time and ease of use. The method is using CFCs for infrared spectroscopy and was withdrawn by ASTM in 2013. This withdrawl marked the end of a long history using CFCs for infrared spectroscopy. Till the end this infrared test method still found use in spectroscopic applications at many industrial sites and remote places.
Since 1980 the infrared based method ASTM D3921 was the standard method for measuring total petroleum hydrocarbon concentrations in water. ERACHECK is using the test method ASTM D7678 which is a very useful alternative for ASTM D3921 since 2011. (Andreas Schwarzmann, R&D)
In 1989 the phase out of ozone-depleting substances (CFCs and HCFCs) was planned by the Montreal Protocol. The infrared test methods continuously started to become replaced by gravimetry (e.g. EPA 1664A) or gas chromatography (e.g. ISO 9377-2). However, the alternative methods require more laborious and careful operation in a laboratory environment.
ASTM D3921 requires the use of the extraction solvent 1,1,2-trichloro-1,2,2-trifluoroethane.