New CE-ESI-MS analytical method for the separation, identification and quantification of seven phenolic acids including three isomer compounds in virgin olive oil.
A sensitive and expeditious CE-ESI-MS analytical method for the separation, identification and determination of seven selected antioxidants (cinnamic and benzoic acids), including three isomers of coumaric acid (ortho-, meta- and para-) has been developed. In order to obtain the analytical separation, capillary electrophoresis and CE-MS interface parameters (e.g., buffer pH and composition, sheath liquid and gas flow rates, sheath liquid composition, electrospray voltage, etc.) were carefully optimized. The polar fraction containing the selected phenolic acids was obtained using a previously optimized SPE pretreatment. An MS detector in order to extract structural information about the target compounds and facilitate their qualitative analysis was used in the negative ion mode. The proposed off-line SPE CE-ESI-MS method was validated by assessing its precision, LODs and LOQs, linearity range and accuracy. The optimized and validated method was used in order to quantify the selected antioxidants in various samples of virgin olive oil and extra-virgin olive oil obtained from the main olive varieties cropped in Castilla-La Mancha, Spain. Salicylic acid was used as internal standard throughout in order to ensure reproducibility in the quantitative analysis of the oil samples. The results confirmed the presence of hydroxyphenyl acetic, p-coumaric, ferulic and vanillic acids in substantial amounts (microg g(-1) level) in all samples.
Nevado
Juan José Berzas
JJ
Department of Analytical Chemistry and Food Technology, University of Castilla-La Mancha, 13071 Ciudad Real, Spain. juanjose.berzas@uclm.es
Peñalvo
Gregorio Castañeda
GC
Robledo
Virginia Rodríguez
VR
Martínez
Gabriela Vargas
GV
D000975:Antioxidants / Q000032:analysis / Q000302:isolation & purification*; D019817:Benzoic Acid; D002934:Cinnamates; D003373:Coumaric Acids; D019075:Electrophoresis, Capillary / Q000379:methods; D062385:Hydroxybenzoates / Q000032:analysis / Q000302:isolation & purification*; D007536:Isomerism; D000069463:Olive Oil; D010938:Plant Oils / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D053719:Tandem Mass Spectrometry
D000975:Antioxidants; D002934:Cinnamates; D003373:Coumaric Acids; D062385:Hydroxybenzoates; D000069463:Olive Oil; D010938:Plant Oils; C029010:cinnamic acid; D019817:Benzoic Acid; C017616:phenolic acid