Quantitative determination of some water-soluble B vitamins by kinetic analytical method based on the perturbation of an oscillatory reaction

Abstract

Um novo procedimento para a determinação da cinética de algumas vitaminas solúveis em água do grupo B (tiamina (B 1), riboflavina (B 2), niacina (B 3) e piridoxina (B 6)), pelas perturbações da concentração do sistema químico oscilatório de Bray-Liebhafsky (BL), na presença de íons iodeto e de hidrogênio é proposto e validado. O método usa um eletrodo de Pt para o monitoramento potenciométrico das perturbações de concentração da matriz BL em um estado estacionário de não equilíbrio, estável, próximo ao ponto de bifurcação. O método proposto baseia-se na relação linear entre as diferenças de potencial máximas, DE m , causadas pelas quantidades adicionais conhecidas da espécie B. Sob condições analíticas ótimas, curvas de calibração lineares foram obtidas no intervalo de 0

Determination of experimental conditions for examination of analytes in Bray-Liebhafsky oscillatory reaction in open reactor conditions

“…S obzirom da je BL oscilatorna reakcija i dalje nepoznanica, ponašanje matrice pri perturbaciji analitom, može da doprinese i proširivanju saznanja o samom ocilatornom sistemu. Do sada je BL reakcija, u uslovima otvorenog reaktora, uspešno korišćena za određivanje koncentracije kvercetina [12,13], rutina [14], hesperidina [15], polimernog nosača [16], paracetamola [17], morfina [18], 6-O-acetilmorfina [19], askorbinske kiseline [20] , vitamina B grupe (B1, B2, B3 i B6) [21], mokraćne kiseline [22] i piroksikama [23] Cilj ovog rada je pronalaženje eksperimentalnih uslova u otvorenom reaktoru za ispitivanje širokog spektra analita u BL reakciji. Pronalaženje pomenutih uslova vrši se bifurkacionom analizom i predstavlja prvi korak u ispitivanju analita, njegovih fizičko-hemijskih svojstava, koncentracije, ali i mehanizma delovanja u BL sistemu.…”

Kinetic analytical method for determination of uric acid in human urine using analyte pulse perturbation technique

“…The preparatory procedure took about 50 min. Conditions similar to the BL reaction for the development of the procedure for the determination of both dynamic states of the BL reaction 29 and vitamins of B group, 18 but it should be pointed out that the examined inflow concentrations of H 2 SO 4 reported here are varied in broader interval from those used in literature. 18 Procedure B…”

“…As previous underlined, 17,18 the experimental conditions for application of the proposed analytical method should be optimized, including the location of the actual bifurcation point in the parameter phase space (bifurcation analysis), the selection of dynamic states that are to be perturbed and the influence of the selected dynamic state on the sensitivity of the matrix system. As previously described, 29 two bifurcation points were found, the lower bifurcation point for [H 2 SO 4 ] 0 = 5.57 × 10 -2 mol L -1 as well as the higher one for [H 2 SO 4 ] 0 = 7.95 × 10 -2 mol L -1 .…”

“…15 Generally, kinetic methods based on the ability of the examined substances to change kinetic parameters of chemical reactions, particularly oscillating chemical reactions, have become remarkably important in view of their comparative advantages; oscillating chemical reactions and their extreme sensitivity to external perturbations make these systems, as matrices, particularly interesting for designing kinetic methods of analysis for the determination of different biologically and pharmaceutically important compounds. [16][17][18][19][20][21] When the oscillatory reaction is the matrix, two distinct methods have been proposed. The first above-mentioned method 19 is based on the relationship between the concentrations of analyte and the response of the matrix in the oscillatory state with respect to the main characters of oscillations, such as amplitude, period and others.…”

“…The first above-mentioned method 19 is based on the relationship between the concentrations of analyte and the response of the matrix in the oscillatory state with respect to the main characters of oscillations, such as amplitude, period and others. In the second method [16][17][18] based on perturbing the Bray-Liebhafsky (BL) oscillatory reaction as matrix in a stable stationary state in the vicinity of a bifurcation point the relationship between maximal potential displacement (DE m ) in the moment of the perturbation and the analyte concentrations would be analyzed. However, using of analyte pulse perturbation (APP) technique in both oscillatory 19 and stable steady state in vicinity of bifurcation point, [16][17][18] the use of the largest Lyapunov exponent 22 and the high-sensitive oscillating chemical system 23 make the technique almost perfect and consequently favorable to use it in real routine analysis.…”