Spectrophotometric Determination of BHA and BHT in Vegetable Oils

Abstract

Improved spectrophotometric methods have been developed for separate determinations of BHA and BHT in vegetable oils. The methods are applicable in the presence of other synthetic antioxidants and are adaptable to BHA and BHT concentrations ranging from 5 to 200 ppm. BHA is nitrosated directly in the oil and the nitroso product is isolated by a combination of solvent extraction and liquid chromatographic techniques. An alkaline solution of the product is measured spectrophotometrically at 480 mμ, and the absorbance is referred to a calibration curve to determine the BHA concentration. Both the 2- and 3-isomers yield approximately the same absorptivity, and Beer's Law is obeyed from 0 to 50 μg BHA/ml final solution. BHT is determined by its ultraviolet absorption at 283 mμ. The compound is separated from the oil by direct extraction into acetonitrile. BHT is isolated from BHA and other extraneous materials by chromatography on alumina

Pulse voltammetric determination of butylated hydroxytoluene in transformer oils

“…Transformer oils are expected to give trouble-free service over long periods (12)(13)(14)(15) years) under extreme climatic temperature variations. Current usage involves adding an antioxidant or combinations thereof to inhibit ageing; e.g., Hydro Quebec adds 800 ppm of 2,6-di-tert-butyl-4-methyl phenol (BHT) (1) to new oils and 3000 ppm to regenerated oils.…”

“…Thin layer chromatography followed by photometric detection, UV (6)(7)(8)(9) or IR (10), or after reaction with 2,6-dichloroquinone-4-chloroimide (11) or phosphomolybdic acid (4), or other color developers (6,12) probably constitutes the most widely used semiquantitative analytical technique, especially for the analysis of food additives. Alumina (13,14) and silica gel (15) have also been used in column chromatography coupled with a liquid-liquid extraction (16). Vapor phase chromatography has been employed for oils and fats (16)(17)(18) and transformer oils (15) using temperature programming and a flame ionization detector or mass spectrometer (6) in order to enhance the sensitivity.…”

“…Spectrophotometric analysis of vegetable oils with a detection limit of 40 ppm BHT has been reported (1,7,13). But the wavelength employed, 275-285 nm, is obviously unsuitable for mineral oils containing an appreciable fraction of aromatic and polyaromatic components.…”

Fluorimetric determination of butylated hydroxy anisole in food products and packaging material

“…Because of these factors, BHA can be determined with BHT and PG present in solution. Problems with colorimetric methods such as differences in reaction rates of the isomers of BHA with a color reagent and differences in molar absorptivities of the final color complex do not occur with fluorimetric methods (Johnson, 1967;Chapman, 1951, 1952). These problems are eliminated because a solution of the isomers gives only one maximum emission wavelength.…”

“…McCaulley et al (1967) have developed a vacuum sublimation method for isolating the antioxidants BHA, BHT, Ionox-100, PG, THBP, and TDPA from lard and quantitatively determining the antioxidants by gas chromatography. Johnson (1967) took advantage of the open ortho position in the BHA molecule to form a colored nitroso derivative, and spectrophotometrically determined BHA in vegetable oils. Recently Takahashi (1967) developed a gas chromatographic method using a hydrogen flame ionization detection system to determine BHA and BHT in ready-to-eat corn and rice cereals.…”