2020 Volume 27 Issue 2 Pages 42-52
A simple and reliable high-performance liquid chromatography (HPLC) method for the determination of quercetin (QR) was developed. The method requires no QR reference; instead, it uses relative molar sensitivity (RMS) to a single reference, methylparaben (MPB). The RMS of QR/MPB was determined using an offline combination of 1H-quantitative NMR (1H-qNMR) and HPLC/UV or HPLC/photodiode array (PDA). In this study, the RMS represents the sensitivity ratio of QR to MPB per mole under defined HPLC conditions. The QR in two natural food additives was quantified using three different techniques such as 1H-qNMR, UV–Vis spectrophotometry, and our single-reference HPLC method. Based on certain amounts of QR in two food additive products, the similar results using 1H-qNMR (mass fraction: 96.9% and 96.1%) and single-reference HPLC (95.8% and 95.0%) were exhibited. On the other hand, the results using UV–Vis spectrophotometry (98.5% and 99.2%) without separation of QR and others (kaempferol and isorhamnetin impurities) showed slightly higher amounts than other techniques. In these techniques, the single-reference HPLC is advanced for the simple and accurate quantification of QR in food additive products without native standard.
