Nano- and rapid resolution liquid chromatography-electrospray ionization-time of flight mass spectrometry to identify and quantify phenolic compounds in olive oil
The applicability of nano-liquid chromatography coupled to electrospray ionization-time of flight-mass spectrometry (nanoLC-ESI-TOF MS) for the analysis of phenolic compounds in olive oil was studied and compared with a HPLC method. After the injection, the compounds were focused on a short capillary trapping column (100 μm i.d., effective length 20 mm, 5 μm particle size) and then nanoLC analysis was carried out in a fused silica capillary column (75 μm i.d., effective length 10 cm, 3 μm particle size) packed with C18 stationary phase. The mobile phase was a mixture of water + 0.5% acetic acid and acetonitrile eluting at 300 nL/min in a gradient mode. Phenolic compounds from different families were identified and quantified. The quality parameters of the nanoLC method (linearity, limits of detection and quantification, repeatability) were evaluated and compare to those obtained with HPLC. The new methodology presents better sensitivity (reaching LOD values below 1 ppb) with less consumption of mobile phases, but worse repeatability, especially inter-day repeatability, doing more difficult to get highly accurate quantification. The results described in this paper open up the application fields of this technique to cover a larger variety of compounds and its advantages will make it especially useful for the analysis of samples containing low concentration of phenolic compounds, as for instance, in biological samples.Ministry of Education and Science (FPU, AP2005- 4356 and Proyect AGL 2008-05108-CO3-03/ALI), and Junta de Andalucía (Proyect P07-AGR-02619)
