Determination of quaternary, ternary, and binary mixtures and single determination of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tert-butylhydroquinone (TBHQ), and nordi-hydroguaiaretic acid (NDGA) have been made by using a partial least-squares (PLS) model. A calibration set containing between 2 to 80 μg mL−1 of BHA, TBHQ, and NDGA and 10 to 200 μg mL−1 of BHT was used, and a model was optimized by using a cross-validation process. Relative standard deviation values between 0.1 and 2.1% for BHA, between 0.2 and 2.1% for BHT, between 0.4 and 8.3% for NDGA, and between 1.2 and 1.3 for TBHQ were calculated. The resolution of quaternary mixtures was tested in sunflower oil samples.
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