New ASTM Test Method Offers Quick and Easy Oil and Grease Measurement for Water and Soil Samples

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Courtesy of Spectro Scientific

Onsite Field Measurement of Oil and Grease

A quick and easy field analysis method for determining oil and grease concentration levels is important for both offshore oil platforms and soil remediation sites.. Prior to the Montreal Protocol, infrared (IR) analysis using Freon as an extraction solvent was a widely used field and laboratory method. In 1999, the U.S. EPA promulgated Method 1664A to replace existing Freon methods. Method 1664A uses gravimetric analysis and hexane for the extraction process rather than Freon. Gravimetric analysis is a laboratory method and cannot be transported to the field for onsite measurements. In addition, hexane is not a suitable solvent for infrared analysis using transmission sampling techniques as it contains hydrocarbons. Therefore, the hexane must be removed through evaporation. If not, the hydrocarbons in the hexane will contribute to the oil and grease concentration measurement. Because of the measurement capabilities, simplicity and portability of infrared analysis, the ASTM felt it was important to find an alternate solvent to Freon and develop a suitable infrared oil and grease method.

New ASTM Method D7066-04

With the manufacture of Freon 113 banned by the Montreal Protocol in 1995, the old ASTM method (D 3921) that used infrared analysis and Freon 113 had to be replaced. Numerous oil and grease applications including U.S. EPA Methods 413.2 and 418.1 and ASTM Method D 3921 used Freon as the extraction solvent. The new ASTM Method D 7066 – 04, Standard Test Method for dimer/trimer of chlorotrifluoroethylene (S-316) Recoverable Oil and Grease and Nonpolar Material by Infrared Determination, uses a similar extraction procedure with a more ozone friendly solvent called S-316.

A variety of infrared instruments can be used with ASTM Method D 7066-04, from full spectrum Fourier Transform Infrared (FTIR) spectrometers to portable, relatively inexpensive fixed filter infrared analyzers such as the Wilks InfraCal TOG/TPH Analyzer in Figure 1. FTIR spectrometers can be found in most testing laboratories and are used for many applications in addition to oil and grease analysis. Portable, fixed filter infrared analyzers are application specific which makes them easier to use in the field or in-plant by personnel with relatively little training.

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