Assay of flavanones in commercial beverages by UHPLC-ESI-MS/MS and isotope dilution methods.

摘要

Standard compounds were chosen having already been detected in different fruits and beverages. The fol lowing substances were selected within flavanones subclass: neohesperidin, neoeriocitrin, neoponcirin, narirutin, hesperitin, naringin, hesperidin, eriocitrin, eriodictyol, poncirin, naringenin, brutieridin, melitidin. The chromatographic conditions have been optimized using acetonitrile and water (0.1% formic acid) as mobile phase. The stationary phase of choice was a C -18. In this study, the best performance for the stan dards resulted using a 300uL/min flow rate. Under the applied conditions, a separation of compounds of interest is achieved within 11 min. For the MRM experiment, MS/MS parameters were optimized for all the analytes in both positive and negative ESI mode. In the positive mode, higher signal intensities of the precursor ion were obtained for most of the analytes. Most of the compounds, once fragmented, highlighted as the most abundant peak of the MS/MS spectra the aglycone fragment; the latter was then chosen as transition for the assay. The calibration curve, used for the assay of flavanones within beverages, has been obtained by injecting the standard solutions of O-methoxyflavanoxime and internal standard d_3-O-methoxyflavanoxime. The first was used at concentrations ranging from 0.25 to 1.2 mg/L, while the latter was kept constant at 0.2 mg /L. Good linearity was obtained for all the anaytes. Analytical parameters were calculated for 1 and 24 mg/L spiked samples, and corroborates the purposed approach. The values of the relative standard deviation (RSD; %) of the calculated concentration show ed a satisfying degree of reproducibility. LOD values were calculated ranging 0.05 -0.29 mg/L, while LOQ values were found 0.04-0.20 mg/L (Tab 1). Further, the values of the method accuracy were obtained ranging from 95.4% to 111.3%. The contents of 13 flav anones in 6 different fruit juice collected from a local store have been determined (Tab 2).