ANALYSIS OF FATS, OILS AND GREASE BASED ON HEXANE EXTRACTION AND INFRARED ABSORPTION

New limits for Fats, Oils and Grease (FOG) are forcing industries to monitor their effluent more frequently to ensure compliance. Waiting for a remote laboratory result could mean discharging effluent above the regulatory limit. An accurate, quick and simple form of analysis can greatly assist an operator. This can be accomplished in the field with a new simplified procedure for FOG analysis based on hexane extraction and infrared absorption.The EPA defines oil and grease as “hexane extractable material”. With an ATR (Attenuated total reflection) sample plate, a measured amount of the hexane extract containing FOG is deposited on the ATR crystal. The hexane evaporates leaving a film of FOG. The plate is installed on a portable infrared filtometer that contains an optical filter isolating the C-H (hydrocarbon) absorption band. FOG concentration is then measured without the hydrocarbon interference from hexane. The whole analysis, from sample collection, extraction to final result, takes under 15 minutes.