Oil in Water Measurement

Since 1980 the infrared based method ASTM D3921 was the standard method for measuring total petroleum hydrocarbon (TPH) concentrations in water. This method requires the use of the extraction solvent 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113, Freon).

In 1989 the phase out of ozone-depleting substances (CFCs and HCFCs) was banned by 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, these other methods require more laborious and careful operation in a laboratory environment.

The infrared test method ASTM D3921 still found use in spectroscopic applications at many industrial sites and remote places. Its unique advantages like accuracy, short measurement time and ease of use maintained its role as an important test method. In 2001 the related Freon-based standard method DIN38409-H18 was withdrawn.

Finally in 2012 the ASTM 3921 standard came into discussion for withdrawal, marking the end of a long history using CFCs for infrared spectroscopy.

In 2011 the new standard method ASTM D7678 was published by ASTM International. It uses environment-friendly cycloalkanes for the extraction rather than CFCs. This method and the availability of new infrared lasers allows the transition from old CFC-based methods while maintaining the advantages of infrared spectroscopy.

By the invention of midinfrared quantum cascade lasers (QCL) a new form of liquid spectroscopy became possible. Eralytics GmbH (Austria) uses this QCL technology within the portable and field-proven ERACHECK instrument. The ERACHECK enables fast, easy and reliable measurements in harsh environments. And moreover this instrument is complying with the new standard method ASTM D7678.