DLLME and MCR-ALS for the resolution and determination of phenolic acids in VOO by RRLC-DAD

M.P. GODOY-CABALLERO; M.J. CULZONI; M.I. ACEDO-VALENZUELA; T. GALEANO-DÍAZ

Congreso; VIII Colloquium Chemometricum Mediterraneum; 2013

Phenolic compounds are part of the minor fraction of compounds in virgin olive oil (VOO) which constitutes approximately 2 % by weight of total. The interest in the study and analysis of them is related to the fact that they act as natural antioxidants and may contribute to the prevention of human disease. In addition, they also contribute to the sensory properties of VOO as well as to its stability [1]. This work presents the development of a rapid resolution liquid chromatography method coupled to UV-visible detection (RRLC-DAD) combined with multivariate curve resolution-alternative least-squares (MCR-ALS) approach to carry out the resolution and quantification of a mixture of five phenolic acids in VOO samples, employing a reversed phase dispersive liquid?liquid microextraction (RP-DLLME). The modeling strategy involves the building of a single MCR-ALS model composed of matrices augmented in the temporal mode, namely spectra remain invariant while time profiles may change from sample to sample. 4-Hydroxybenzoic (4HB), gentisic (GEN), vanillic (VAN), caffeic (CAF) and syringic (SY) acids have been chosen as a representative group of phenolic compounds. All of them present different absorption spectra and overlapped time profiles with the olive oil matrix interferences and between them. So MCR-ALS is used to cope the coeluting interferences on account the second order advantage inherent to this algorithm. Initially, a set of 9 calibration samples were randomly prepared, in a concentration range from 0.5 to 5 μg·mL-1 for all phenolic acids. The validation was firstly carried out using standard mixtures of these acids in ethanol:water (60:40, v/v) and, secondly, in real VOO samples getting good results in both cases.