ABSTRACT
A smartphone-assisted, paper-based ratio fluorescence probe is presented for the rapid, low-cost and on-site quantification of total flavonol glycosides in Ginkgo biloba extracts (GBE). The Al3+/Eu-MOF/paper-based probe utilizes lanthanide metal-organic framework (Ln-MOF) nanoparticles immobilized on Whatman filter paper along with Al3+ for detecting flavonols, which are the hydrolyzed products of flavonol glycosides. The color change of the paper-based fluorescence image from red to orange depends on the concentration of the target analyte in the sample solution. The smartphone equipped with a red, green, blue (RGB) color detector measured the fluorescence signal intensity on the paper substrate after adding flavonol. The analytical variables affecting the performance of the probe, including the addition sequence of the aluminum nitrate solution, its concentration, that of the Ln-MOF solution, the drying time of the paper probe, the reaction time and the sensitivity parameters of the mobile phone camera (ISO), were optimized. Under optimal conditions, the Al3+/Eu-MOF/paper-based probe has good linear response in the concentration range 7 ~ 80 µg mL- 1 and a lower detection limit of 2.07 µg mL- 1. The results obtained with the paper-based ratio fluorescence probe and smartphone combination were validated by comparing them with high-performance liquid chromatography (HPLC) measurements. This study provides a potential strategy for fabricating Al3+/Eu-MOF/paper-based probe used for total flavonol glycosides determination.
Subject(s)
Lanthanoid Series Elements , Metal-Organic Frameworks , Smartphone , Diagnostic Imaging , Flavonols , Glycosides , Plant ExtractsABSTRACT
Objective To develop a HPLC method for the determination of the total flavonol glycosides in health food by acid hydrolysis. Methods The sample was extracted by methanol and was hydrolyzed into 3 aglycones by acid hydrolysis. They were quercetin, kaempferide and isorhamnetin. Chromatographic separation was carried out by the method of HPLC. The content of total flavonol glycosides was calculated. Results Methanol -25% hydrochloric acid solution (4:1) was added into selected samples, then 85 ℃ water bath heating and refluxing were conducted for 30 min. Optimum chromatographic conditions were as follows. Chromatographic column: ODS C18 (150 mm ×4.6 mm,5μm) . Mobile phase: used methanol-0.6% phosphoric acid (47:53) . Column temperature was set at 35 ℃. Detection wavelength was 360 nm. The linear ranges of quercetin, kaempferide and isorhamnetin were (4.766-95.52) μg/mL(r=0.9991) , (5.052-101.0) μg/mL (r=0.9994) and (2.027-48.66) μg/mL (r=0.9994) respectively. The relative standard deviation of the samples was 0.57%. The recovery rate was 98.25% (RSD=3.82%), 99.81% (RSD=3.31%) and 101.8% (RSD=4. 86%) . The detection limits of quercetin and kaempferide were both 0.50 μg, while Isorhamnetin was 0.80 μg, the total flavonol glycosides was 4.52 μg. The content of total flavonol glycosides detected by this method was lower than the content of the total glavonoids detected by the method provided by technical specification for inspection and evaluation of health food (2003 Edition) . Conclusion This method proved to be simple, stable and had strong repeatability and could be used for the determination of total flavonol glycosides in health food.
ABSTRACT
Objective To determine the best extraction process of ginkgo leaves with the total transfer rate of total flavonol glycosides and terpene lactones as the index.Methods The effects of ethanol concentration, solid-liquid ratio and extraction time on extraction process were investigated by orthogonal design method, and the contents of total flavonol glycosides and terpene lactones were detected by HPLC to calculate transfer rate.Results The optimum extraction conditions were as follows:85% ethanol refluxing and extracting for three times;the first time extracting with five-fold amount of solvent (V/W) for 3 hours;the last two times with three-fold solvent (V/W) for 2 hours.Conclusion This extraction process has the advantages of simplicity of operator, reason, energy conservation, high efficiency, and is suitable for industrial production.
