Normal Flow and Stopped Flow Injection Spectrophotometric Determination of Quercetin Dihydrate Dietary Supplements

Simple and sensitive normal flow injection (nFI) and stopped-FI spectrophotometric methods for the determination of quercetin dehydrate (QRC) in pure form were proposed, The methods were based on diazotization and coupling reaction between QRC and diazotized metoclopramide in alkaline medium to form orangewater soluble dye. The dye is stable and has a maximum absorbance at 438nm. A calibration graph shows that a Beers law is obeyed over the concentration range of 1-60g. ml-1 and 0.8-50g. ml-1 for (QRC) with a detection limit is 0.4166 g. ml-1, 0.1338 for nFI and stopped-FI methods, respectively. The reproducibility percentage (RSD % is 1.528 and 1.695 for both nFI and stopped-FI methods, and recovery percentage Rec % is (101.527) for nFIA and (104.36) for stopped-FIA. In nFIA the chemical and physical parameters are studied. The proposed method was applied on dietary supplements such as (Mega quercetin, Quercetin dehydrate).