Određivanje kvercetina u farmaceutskim preparatima preko reakcije sa kalijum-titaniloksalatom - određivanje konstanti stabilnosti kvercetin-titaniloksalatnog kompleksa
| Autor: | L Dusan Malesev, S Vesna Kuntic, Svetlana Micic, D Natasa Pejic, B Zorica Vujic, Vladana Vukojević |
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| Rok vydání: | 2005 |
| Předmět: |
Potassium
dosage form chemistry.chemical_element 010402 general chemistry 01 natural sciences Dosage form quercetin lcsh:Chemistry symbols.namesake chemistry.chemical_compound Detection limit Chromatography Vitamin C 010401 analytical chemistry Beer–Lambert law spectrophotometric determination General Chemistry Molar absorptivity Ascorbic acid 0104 chemical sciences stability constants lcsh:QD1-999 chemistry symbols Quercetin potassium titanyloxalate |
| Zdroj: | Journal of the Serbian Chemical Society Journal of the Serbian Chemical Society, Vol 70, Iss 5, Pp 753-763 (2005) |
| Popis: | Asimple, rapid and accurate procedure for the quantitative determination of quercetin in its pure form and in formulations has been developed. The method is based on the spectrophotometric determination of a complex formed between quercetin and potassium titanyloxalate in 50 % ethanolic solutions. To characterize the quercetin titanyloxalato complex, the stability constants of the complex were determinated potentiometrically and spectrophotometrically at different temperatures (T = 26.0oC, 34oC and 39.0oC), as well as at different ionic strengths (I = 5.0x10-4 mol dm-3, 3.0x10-2 mol dm-3 and 6.0x10-2 mol dm-3) and the thermodynamic parameters were calculated. As quercetin is usually conjugated to vitamin C in pharmaceutical formulations, two procedures for the quantitative determination of quercetin by this complexing reaction were tested - both in the absence and presence of ascorbic acid. In both procedures, the Beer law was obeyed over the same concentration range of quercetin, i.e., 0.85 μg mL-1 - 16.9 μg mL-1. In the first procedure in the absence of ascorbic acid the molar absorptivity coefficient of the quercetin-titanyloxalate complex is a=2.49 x 104 mol-1 dm3 cm-1, Sandells sensitivity of the method is S = 1.35 x 10-2 μg cm-2 and the detection limit is d = 0.67 μg mL-1. Whereas, in the presence of ascorbic acid (second procedure) a = 3.04 x 104 mol-1 dm3 cm-1, S = 1.11 x 10-2 μg mL-1. The proposed method was verified for the determination of quercetin in pharmaceutical dosage forms. Predložen je brz, jednostavan i tačan metod za određivanje kvercetina u farmaceutskim sirovinama i doziranim oblicima.Metod je baziran na spektrofotometrijskom određivanju kompleksa formiranog između kvercetina i kalijum-titaniloksalata u 50 % etanolu. Određene su konstante stabilnosti kvercetin titaniloksalatnog kompleksa potenciometrijski i spektrofotometrijski na različitim temperaturama (T = 26.0oC, 34oC and 39.0oC) i jonskim jačinama (I = 5.0x10-4 mol dm-3, 3.0x10-2 mol dm-3 and 6.0x10-2 mol dm-3) i izračunati su termodinamički parametri. Kako se kvercetin uobičajeno nalazi zajedno sa vitaminom C u doziranim oblicima, predložene su dve procedure za određivanje kvercetina: bez i u prisustvu askorbinske kiseline.U obe predložene procedure, Beer-ov zakon važi u oblasti 00.85 μg mL-1 - 16.9 μg mL-1 kvercetina. Prema prvoj proceduri, molarni apsorpcioni koeficijent kvercetin–titaniloksalatnog kompleksa je a=2.49 x 104 mol-1 dm3 cm-1, Sandelova osetljivost metode je S = 1.35 x 10-2 μg cm-2, a limit detekcije je d = 0.67 μg mL-1. Prema drugoj proceduri, a = 3.04 x 104 mol-1 dm3 cm-1, S = 1.11 x 10-2 μg mL-1. Predloženi metod je primenjen za određivanje kvercetina u doziranim oblicima. |
| Databáze: | OpenAIRE |
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