[Determination of Hesperidin and Monoglucosylhesperidin Contents in Processed Foods Using Relative Molar Sensitivity Based on 1H-Quantitative NMR].

We designed an off-line combination of HPLC/photodiode array detector (PDA) and 1H-quantitative NMR (1H-qNMR) to estimate the relative molar sensitivity (RMS) of an analyte to a reference standard. The RMS is calculated as follows: a mixture of the analyte and the reference is analyzed using 1H-qNMR and HPLC/PDA. The response ratio of the analyte and the reference obtained by HPLC/PDA is then corrected using the molar ratio obtained by 1H-qNMR. We selected methylparaben (MPB), which is a certified reference material, as the reference standard and hesperidin (Hes) and monoglucosylhesperidin (MGHes) as analytes, and the RMSs of Hes283 nm/MPB255 nm and MGHes283 nm/MPB255 nm were determined as 1.25 and 1.32, respectively. We determined the contents of Hes and MGHes in processed foods by the conventional absolute calibration method and by the internal standard method employing the RMS values with respect to MPB. The differences between the values obtained with the two methods were less than 2.0% for Hes and 3.5% for MGHes.