FORMULATION AND ANALYSIS OF FOOD-GRADE MINERAL HYDROCARBONS IN TOXICOLOGY STUDIES

Methods are presented for the formulation and rapid determination of m ineral hydrocarbons (MHCs) in animal diet and tissue. Food grade white oils and low melting point waxes are mixed as liquids with powdered d iet. Higher melting point waxes are first powdered using a novel atomi zation technique before dry mixing with diet. MHCs sufficiently solubl e in carbon tetrachloride (CCl4) are determined in diet by ultrasonic solvent extraction, adsorption of polar material on Florisil and analy sis of the residue by quantitative Fourier Transform Infra Red (FT-IR) spectroscopy. Quantification in tissue is achieved by aqueous saponif ication, followed by extraction, dean-up and FT-IR analysis as for die t samples. A 10-fold increase in sensitivity over previous methods is achieved, below 0.002% (w/w) in diet and 0.1 mg/g in tissue. Over 80% of the CCl4 used can be recovered and recycled. Control diet seems to contain approximately 0.003% (w/w) background MHC. The method was modi fied for one powdered wax, only sparingly soluble in CCl4, high concen trations being extracted from diet by flotation in aqueous cetrimide a nd determined gravimetrically with a limit of detection of 0.1% (w/w) in diet. Application of these methods to 90-day feeding studies is des cribed, and future developments due to the phasing out of CCl4 are dis cussed.