Determination of tert-butylhydroquinone in vegetable oils using surface-enhanced Raman spectroscopy

Monitoring the level of tert-butylhydroquinone (TBHQ), a permissible antioxidant additive in edible vegetable oils in many countries, is important to ensure that oils and products that contain them comply with the relevant import regulations. Surface-enhanced Raman spectroscopy (SERS) technology coupled with chemometric methods including partial least squares (PLS) and support vector machine (SVM) regression was applied to determine levels of TBHQ in spiked corn oils (0 to 500 mg/kg, n = 40) and commercial vegetable oils (0 to 99.7 mg/kg, n = 25). The lowest detectable concentration was 5 mg/L for TBHQ in standard solutions and 10 mg/kg of TBHQ in vegetable oils from various plant sources. The TBHQ levels predicted by the PLS or SVM model had a high correlation with actual TBHQ levels in commercial oil samples (SVM: R(2) = 0.972, ratio of performance to deviation [RPD] = 5.55, root mean square error [RMSE] = 5.73 mg/kg; PLS: R(2) = 0.976, RPD = 6.43, RMSE = 4.94 mg/kg), indicating great potential of SERS methods for detection and quantification of TBHQ in oils from a variety of sources.

This study provides an alternative approach for analysis of trace amounts of chemicals in complex food matrices with surface-enhanced Raman spectroscopy.