Fluorimetric Determination of Some Sulfur Containing Compounds Through Complex Formation with Terbium (Tb+3) and Uranium (U+3)

Abstract

Two simple, sensitive and specific fluorimetric methods have been developed for the determination of some sulphur containing compounds namely, Acetylcysteine (Ac), Carbocisteine (Cc) and Thioctic acid (Th) using terbium Tb+3 and uranium U+3 ions as fluorescent probes. The proposed methods involve the formation of a ternary complex with Tb+3 in presence of Tris-buffer method (I) and a binary complex with aqueous uranyl acetate solution method (II). The fluorescence quenching of Tb+3 at 510, 488 and 540 nm (lambda(ex) 250, 241 and 268 nm) and of uranyl acetate at 512 nm (lambda(ex) 240 nm) due to the complex formation was quantitatively measured for Ac, Cc and Th, respectively. The reaction conditions and the fluorescence spectral properties of the complexes have been investigated. Under the described conditions, the proposed methods were applicable over the concentration range (0.2-2.5 microg ml(-1)), (1-4 microg ml(-1)) and (0.5-3.5 microg ml(-1)) with mean percentage recoveries 99.74+/-0.36, 99.70+/-0.52 and 99.43+/-0.23 for method (I) and (0.5-6 microg ml(-1)), (0.5-5 microg ml(-1)), and (1-6 microg ml(-1)) with mean percentage recoveries 99.38+/-0.20, 99.82+/-0.28 and 99.93+/-0.32 for method (II), for the three cited drugs, respectively. The proposed methods were successfully applied for the determination of the studied compounds in bulk powders and in pharmaceutical formulations, as well as in presence of their related substances. The results obtained were found to be in agree statistically with those obtained by official and reported ones. The two methods were validated according to USP guidelines and also assessed by applying the standard addition technique.

Kinetic Spectrophotometric Determination of N-acetyl-L-cysteine Based on the Reduction of Copper(II)-neocuproine Reagent

“…1 The European Pharmacopeia recommended iodimetric titration for pharmaceutical formulations analysis. 2 Other reported methods described in the literature comprise: titrimetry, 3,4 spectrophotometry, [5][6][7][8][9] fluorimetry, [10][11][12] chromatography, 13,14 potentiometry, 15 conductometry 16 and voltametry [17][18][19] for the determination of NAC in pure form, in dosage forms and in biological samples.…”

Flow-injection Spectrophotometric Determination of N-acetyl-L-cysteine Based on Coupled Redox-complexation Reaction

“…In addition, it is being studied and utilized for curing HIV infection, cancer and heart disease. 1 Several analytical methods have been reported for NAC determination in pharmaceutical formulations, including spectrophotometry, [2][3][4][5][6][7] fluorimetry, 8,9 chromatography 10,11 and electrochemistry. 12,13 Some of the methods described above are not simple for direct application in a large-scale routine analysis and require expensive or sophisticated instruments.…”

Untitled

“…Different analytical methods have been published for their determination. The most commonly used methods are spectrophotometric [4][5][6] , spectrofluorimetric [7][8][9] , chromatographic [10][11][12] and electrochemical methods [13][14][15]. …”