Determination of caffeine with the use of effects of the luminescence Tb (III) ion quenching
Journal Title: Фармацевтичний журнал - Year 2014, Vol 2, Issue 2
Abstract
Caffeine is a part of many drugs and is widely used in therapeutic practice; therefore, there is the need for careful control of its dosage. For determination of caffeine used spectrophotometric methods, which are not selective, high performance liquid chromatography methods, which require expensive equipment. The aim of this work was to develop a simple and sensitive methods of quantitative determination of caffeine in pharmaceutical drugs Kofetamin and Piramein quenching effect using caffeine sensitized luminescence of Tb(III) complex with a sorbate 1,10-phenanthroline and β-cyclodextrin in the solid sorbent. The optimum conditions for obtaining the analytical signal of the proposed luminescent sensor have been investigated. It has been shown that the use of β-cyclodextrin as a second ligand promotes the formation of inclusion complexes of "guest-host", which leads to the displacement of water molecules of the inner sphere of the complex, and to reduce non-radioactive energy loss stimulation. As a result, this significantly increases luminescence. It was established that luminescence sorbate concentration dependent on ion Tb (III) in solution at the maximum concentration 1·10-3 mol/l. Under optimal conditions, the luminescence signal is selected as an analytical band luminescence of Tb(III), corresponding to supersensitive transition 5D4 → 7F5 (λemission = 545 nm, λexcitation = 365 nm). It was shown that most effect of luminescence quenching ion Tb(III) in complexes appears in the sorbent phase - silica gel. The optimal conditions of sorption - sorption time, temperature and drying time was studied. The observed effect of luminescence quenching of Tb (III) ion in complex with 1,10-phenanthroline and β-cyclodextrin in the presence of caffeine was used by us at the development of methods for determining the of caffeine in dosage formed. The content of caffeine was found from calibration carve. The detection limit of caffeine is 0.02 µg/ml. The accuracy and reliability of the determination were verified by statistical processing of the results of determination. The relative standard deviation was 1.7–2.6%.
Authors and Affiliations
S. V. Beltyukova, O. I. Teslyuk, Е. О. Liventsova
Keywords
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