A gas liquid chromatographic (GLC) technique has been developed which requires about 20 min for the determination of BHA and BHT in vegetable oils. This method involves the addition of an internal standard to a weighed portion of the oil, dilution of the mixture with carbon disulfide, and injection into the Gas Chromatograph. BHA and BHT are isolated from the nonvolatile vegetable oil by using a short precolumn located in the sample port block of the gas chromatograph. Up to 35 consecutive sample injections per day have been made on the same precolumn with no appreciable effect on the accuracy of the determination. The precolumn is cleaned at the end of each day's operation. The clean precoluran is allowed to equilibrate to sample port block temperature overnight for the following day's analysis. Identification of BHA and BHT can be confirmed with a second GLC column which reverses the elution order of these compounds. Soybean, cottonseed, corn and peanut oils fortified with 20, 60 and 100 ppm each of BHA and BHT showed a recovery range of 97% to 104%.

A simple procedure has been developed for the isolation, concentration and gas liquid chromatographic detection of the volatile compounds in vegetable oils. The votatile compounds are isolated by bubbling purified helium through a measured quantity of vegetable oil heated in an oil bath having a temperature of 350 F. These compounds are collected on activated charcoal and then extracted from the charcoal with carbon disulfide containing an internal standard. The distribution of the volatile compounds is determined with a flame ionization detector. A 400-fold concentration of the volatile compounds is achieved with this procedure. The technique provides good reproducibility (94.3% to 105.5%) and has been successfully used for measuring the increase of volatile compounds in vegetable oils during storage and food production.