Spectrofluorimetric determination of quercetin in pharmaceutical dosage forms

Abstract

A simple, accurate and precise method based on the fluorescence properties of the aluminum(III)-quercetin complex, for the determination of quercetin, has been developed and validated. The complex has strong emission at pH 3.30,  em = 480 nm, with  ex = 420 nm. The linearity range of quercetin determination was 1.5-60.5 ng ml -1 with LOD 0.09 ng ml -1 and LOQ 0.27 ng ml -1. Recovery values in the range of 99.9-100.2% indicate a good accuracy of the method. The established method was applied for the determination of quercetin in capsules, with a recovery value of 98.3%, standard deviation of 0.22% and coefficient of variation of 0.09%.The reliability of the method was checked by the newly developed RP-HPLC/UV method for capsules with the direct determination of quercetin after separation. The good agreement between the two methods indicates the applicability of the proposed spectrofluorimetric method for quercetin determination in pharmaceutical dosage forms, with high reproducibility, and enables the direct and simple determination without its prior extraction from samples.The proposed spectrofluorimetric method has much better sensitivity and LOD and LOQ values that are about 1000 times lower than data reported in the literature.Keywords: quercetin; flavonoids; spectrofluorimetric determination; RP-HPLC; capsules СПЕКТРОФЛУОРОМЕТРИСКО ОПРЕДЕЛУВАЊЕ НА КВЕРЦЕТИН ВО ФАРМАЦЕВТСКИ ДОЗИРАНИ ФОРМИРазвиен и валидиран е едноставен, точен и прецизен метод за определување на кверцетин заснован на флуоресцентните својства на комплексот кверцетин-алуминиум(III). Комплексот покажува силна емисија при pH 3,30,  em = 480 nm и  ex = 420 nm. Линеарниот опсег за определување на кверцетин е 1,5-60,5 ng ml -1 со LOD 0,09 ng ml -1 и LOQ 0,27 ng ml -1. Вредностите на аналитичкиот принос од 99,9-100,2% покажуваат добра точност на методот. Воспоставениот метод е применет за определување на кверцетин во капсули со вредност на аналитичкиот принос од 98.3%, стандардна девијација од 0,22% и коефициент на варијација од 0,09%.Веродостојноста на методот е проверена со новововедениот RP-HPLC/UV метод за капсули со директно определување на кверцетин по негова сепарација. Доброто согласување на двата метода укажува на применливост на предложениот спектрофлуорометриски метод за опреде-лување на кверцетин во фармацевтски дозирани форми со висока репродуцибилност и овозможува директно и едноставно определување без претходна екстракција од примероците.Предложениот спектрофлуорометриски метод има многу подобра осетливост и вредностите LOD и LOQ се за околу 1000 пати пониски од оние дадени во литературата.

Determination of flavonoids and total polyphenol contents in commercial apple juices

“…The high accuracy and repeatability of the method are demonstrated by the low SD values. As we have reported in our previous work, vitamin C does not interfere with spectrofluorimetric determination of quercetin under the established experimental parameters (Pavun et al 2014).…”

“…The spectrofluorimetric determination of the content of flavonoids as QE was adapted from the procedure reported by Pavun et al (2014) for quercetin determination. Spectrofluorimetric determination is based on a calibration curve (I F = (1.47 ± 0.01) × c Querc + (0.56 ± 0.04)), where the intensity of fluorescence (%) (λ ex = 420 nm and λ em = 480 nm) is linearly dependent on the quercetin concentration (expressed as mg/l).…”

Zinc-quercetin complex: From determination to bioactivity

“…Those complexes may be the basis for many methods developed for the determination of both flavonoids and ions. In our previous research, we have developed spectrofluorimetric and spectrophotometric methods based on the complexes formed with metal ions, and successfully applied them for the determinations of several flavonoids in fruit juices and/or pharmaceutical dosage forms (Pavun et al, 2018, Pavun et al, 2016, Pavun et al, 2014.…”

A highly sensitive morin sensor based on PEDT–Au/rGO nanocomposites modified glassy carbon electrode

“…3 Since morin possesses various positive effects, the determination of morin has attracted enormous attention in recent years. Several techniques such as high performance liquid chromatography (HPLC), [11][12][13] nuclear magnetic resonance spectrometry (NMR), 14 uorescence spectrophotometry, 11 ultraviolet spectrophotometry, 15 and electrochemical measurements, 5,8,16 offer available approaches for determination of morin. However, these reported chromatographic and spectroscopic analyses are usually high cost of equipment, time-consuming of operation and require complicated working conditions.…”