Selective UV-spectrophotometric methods for determination of iron(III) in iron(II) samples have been developed. The methods are based on the interaction of Fe(III) with quercetin and morin, compounds ...of the flavonoid group. Redox reactions occurring between Fe(III) ions and the reagents used make the basis for the detection. Iron(II) does not react with quercetin and morin under the conditions applied aqueous-methanolic (3:2) soluions, 0.3 mol L-1 HCl, 1.2 x 10-4 mol L-1 quercetin (morin) and does not interfere with the determination of Fe(III). Iron(III) can be determined up to 15 μg mL-1 using both the examined systems. The detection limits are 0.06 and 0.38 μg mL-1 when using quercetin or morin, respectively. The method with quercetin was applied to the determination of Fe(III) (ca. 0.2%) in a Fe(II) pharmaceutical product.
U radu je opisan razvoj selektivnih UV-spektrofotometrijskih metoda za određivanje željeza(III) u uzorcima željeza(II). Metode se temelje na redoks reakciji Fe(III) sa spojevima iz skupine flavonoida -- kvercetinom i morinom u reakcijskim uvjetima u kojima željezo(II) ne reagira (vodeno/metanolna otopina 3:2, 0,3 mol L-1 HCl, 1,2 x 10-4 mol L-1 kvercetin ili morin). Najniža koncentracija željeza(III) koja se može odrediti u oba ispitivana sustava je 15 μg mL-1. Granice detekcije su 0,06 i 0,38 μg mL-1 ako se koristi kvercetin odnosno morfin. Metoda s kvercetinom primijenjena je za određivanje Fe(III (približno 0,2%) u farmaceutskom proizvodu Fe(II).
The UV-VIS spectrophotometric methods for the determination of Os(VIII) (as OsO
4
) and Os(IV) (as OsCl
6
2−
complex) in their mixtures were developed. Quercetin (Q), a flavonoid compound, was used ...as a chromogenic reagent. Both direct and derivative spectrophotometry can be employed for the determination of Os(VIII). The calculation of the first-derivative spectrum of the examined mixture and the use of the signal at 285.1 nm allows reaching a better detection limit (0.01 µg mL
−1
Os) as compared with direct spectrophotometry (0.1 µg mL
−1
Os). Relative standard deviations of the results are in the range of 0.87%-4.65% and 0.45%-1.15% for direct and derivative mode, respectively. Selective redox reaction of OsO
4
with Q under the conditions used (0.05 M HCl, 1×10
−4
M Q, 15 min heating at 70°C) makes the basis of its determination in mixtures with the OsCl
6
2−
complex. Quercetin does not react with the OsCl
6
2−
complex. The signals of the OsCl
6
2−
complex can be isolated from the examined mixtures by the calculation of the third-order derivative spectra and the use of the values at 340.0 nm. The effectiveness of the reduction of OsO
4
in chloride solutions has been studied by the developed method.
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BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
U radu je opisan razvoj selektivnih UV-spektrofotometrijskih metoda za određivanje željeza(III) u uzorku željeza(II). Metode se temelje na redoks reakciji Fe(III) sa spojevima iz skupine flavonoida ...kvercetinom i morinom u reakcijskim uvjetima u kojima željezo(II) ne reagira (vodeno/metanolna otopina 3:2, 0,3 mol L1 HCl, 1,2 x 104 mol L1 kvercetin ili morin). Najniža koncentracija željeza(III) koja se može odrediti je 15 μg mL1 u oba ispitivana sustava. Granice detekcije su 0,06 i 0,38 μg mL1 ako se koristi kvercetin, odnosno morfin. Metoda s kvercetinom primijenjena je za određivanje Fe(III (približno 0,2%) u farmaceutskom produktu Fe(II).
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