A Simple and Sensitive Inhibitory Kinetic Method for the Carbocisteine Determination

Abstract

Abstract. A fast, reproducible, and sensitive method is proposed for the kinetic determination of carbocisteine (CCys). The method depends on the inhibitory property of carbocisteine, which reduces the Hg2+ catalyzed substitution rate of cyanide from [Ru(CN)6]4- with N-R-salt (1-Nitroso-2-naphthol-3,6-disulfonic acid disodium salt) via forming a stable complex with Hg2+. Spectrophotometric measurements were carried out by recording the absorbance at 525 nm (λmax of [Ru(CN)5 Nitroso-R-Salt]3- complex) at a fixed time of 10 and 15 min under the optimized reaction conditions with [N-R-salt] = 4.5 × 10-4 M, I = 0.05 M (KNO3), Temp = 45.0 ± 0.2 o C, pH = 7.0 ± 0.03, [Hg2+] = 8.0 × 10-5 M and [Ru(CN)64-] = 4.25 × 10-5 M. With the proposed method, CCys can be determined quantitatively down to 3.0 × 10-6 M. This methodology can be effectively used for the rapid quantitative estimation of CCys in the pharmaceutical samples with good accuracy and reproducibility. The addition of common excipients in pharmaceuticals even up to 1000 times with [CCys] does not interfere significantly in the estimation of CCys.
 
 Resumen. Se propone un método rápido, reproducibley sensible para la determinación cinética de la carbocisteina (CCys). El método depende de la propiedad inhibitoria de la carbocisteina que reduce la tasa de sustitución catalizada por Hg2+ del cianuro de [Ru(CN)6]4- con la sal N-R (sal disódica del ácido 1-Nitroso-2-naftol-3,6-disulfónico) mediante la formación de un complejo estable con Hg2+. Las mediciones espectrofotométricas se llevaron a cabo registrando la absorbancia a 525 nm (λmax del complejo [Ru(CN)5 Sal-Nitroso-R]3-) en un tiempo fijo de 10 y 15 min en las condiciones de reacción optimizadas con [sal-NR] = 4.5 × 10-4 M, I = 0.05 M (KNO3), Temp = 45.0 ± 0.2 o C, pH = 7.0 ± 0.03, [Hg2+] = 8.0 × 10-5 M y [Ru(CN)64-] = 4.25 × 10-5 M. Con el método propuesto, CCys se puede determinar cuantitativamente hasta 3,0 × 10-6 M. Esta metodología se puede utilizar eficazmente para la estimación cuantitativa rápida de CCys en las muestras farmacéuticas con buena precisión y reproducibilidad. La adición de excipientes comunes en productos farmacéuticos incluso hasta 1000 veces con [CCys] no interfiere significativamente en la estimación de CCys.

Quantification of alpha-lipoic acid in pharmaceutical samples using Pd(II) catalyzed ligand substitution reaction in SLS micellar medium

“…Kinetic analyses of the Fe(II) and Co(II) complexes oxidation and metal-catalyzed cyanide substitution from [Ru/Fe(CN)6]3-by nitrogen heterocyclic ligands have been reported by a number of authors [25][26][27]. The aforementioned processes have also successfully been employed for the trace-level evaluation of catalysts and medications/moieties that have a profound affinity for catalysts [28][29][30].…”

“…Different methods are frequently employed to quantify thio compounds in analytical, biological, and pharmacological materials. The quantifica,tion methodology includes potentiometry [31], spectrophotometry [32,33], chromatography [34][35][36], fluorimetry [37], NMR-spectrometry [38], flow injection analysis [39], colorimetry [29], and voltammetry [40,41]. Table 1 describes the various analytical methods used for the determination of ALA with their detection limit.…”

Kinetic Study of Ru(III) Promoted Oxidation of L-Tryptophan in an Anionic Surfactant Medium by Hexacyanoferrate(III)

“…Numerous kinetic reports on oxidation of Fe(II)/Co(II) complexes and the metalcatalyzed Hg(II)/Ag(I), cyanide substitution from cyano complexes of Fe(II)/Ru(II) by heterocyclic ligand containing nitrogen has been reported by several authors [19][20][21]. These reactions have also been successfully used for the micro-level quantification of employed catalysts and drugs/compounds that can bind strongly with a catalyst [22][23][24]. Several reports are available on the spectrophotometric determination of various drugs in pharmaceutical preparations [25][26][27].…”

Effect of cationic surfactant on Ru(III) catalyzed L‐glutamic acid oxidation by hexacyanoferrate(III)

“…Several authors have published kinetic reports on the substitution of cyanide from [Fe/Ru (CN) 6 ] 3− catalyzed by metal [Ag(I)/Hg(II)] and the oxidation of Co(II)/Fe(II) complexes 13–15 . Additionally, the trace‐level determination of used catalysts and medications/compounds that shows strong affinity towards catalyst has also been accomplished with success using these reactions 16–18 …”

“…[13][14][15] Additionally, the trace-level determination of used catalysts and medications/compounds that shows strong affinity towards catalyst has also been accomplished with success using these reactions. [16][17][18] Amino acid oxidation is important in medicine and metabolism because organisms strive to maintain protein balance in the body by oxidizing amino acids. Therefore, it is crucial to research the mechanism by which different amino acids are oxidized.…”