Kinetic Spectrophotometric Determination of Thiols and Ascorbic Acid

Martinović, Anita; Kukoc-Modun, Lea; Radić, Njegomir

doi:10.1080/00032710601017938

Cited by 18 publications

(15 citation statements)

References 23 publications

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“…Noteworthy, the same Fe(III)-ligand systems have been successfully used for the kinetic determination of NAC. [8,9] Under the optimum conditions previously reported for NAC we found considerable differences between NAC and NACET (Supplement materials Figure 1 and Figure 2). These results indicate the possibility of determining NAC in the presence of NACET.…”

Section: Reactions Involved and Optimization Of The Experimental Condmentioning

confidence: 69%

“…Among the described indirect spectrophotometric procedures one of the most common approaches to the determination of NAC is based on the coupled redox complexation reaction. The first step is the reduction of Fe(III) by NAC, followed by the determination of produced Fe(II) using various chromogenic reagents: 1,10-phenantroline, [4,8,12] hexacyanoferrate(III), [13] ferrozine, [6] 2,4,6-trypyridyl-striazine [9,18] and ferricyanide. [14] Cu(II)-neocuproine has also been used for the analysis of NAC of which the sulfhydryl group (SH) reduces Cu(II)-neocuproine to the chromogenic Cu(I)-neocuproine.…”

Section: Introductionmentioning

confidence: 99%

“…In the literature, there have been reported many spetrophotometric methods for the determination of NAC. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] One group of described methods involves redox reactions with NAC in which a colored compound is formed or decomposed during determination. Among the described indirect spectrophotometric procedures one of the most common approaches to the determination of NAC is based on the coupled redox complexation reaction.…”

Section: Introductionmentioning

confidence: 99%

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Kinetic Spectrophotometric Determination of N-Acetyl-L-cysteine Ethyl Ester (NACET) Generating Chromogenic Copper(I)Ln Complexes with Different Ligands

Kukoc-Modun¹,

Tsikas²,

Kraljević³

et al. 2017

Croat. Chem. Acta

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Three simple, sensitive and robust kinetic spectrophotometric methods for the determination of a novel lipophilic thiol compound, N-acetyl-L-cysteine ethyl ester (NACET), have been developed and validated. The methods are based on the reduction of Cu(II)-ligand complex to Cu(I)-ligand complex with the analyte. Studied ligands were neocuproine, bicinchoninic acid (BCA) and bathocuproine disulfonic acid (BCS). The development of chromogenic complexes was followed using kinetic setup with spectrophotometric detection at 458, 562 and 483 nm for the reactions of NACET with neocuproine, BCA and BCS, respectively. The calculated reaction orders with respect to NACET concentration were found to be 1.07, 1.01, 1.07, respectively, thus confirming a first order of reaction. The initial rate and fixed time methods were utilized for constructing calibration curves. Assays limits of detection were 1.4 × 10 -7 , 3.2 × 10 −7 and 6.0 × 10 −8 mol L -1 , respectively. The analytical performance of the methods, in terms of accuracy and precision, was established.

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Section: Reactions Involved and Optimization Of The Experimental Condmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Kinetic Spectrophotometric Determination of N-Acetyl-L-cysteine Ethyl Ester (NACET) Generating Chromogenic Copper(I)Ln Complexes with Different Ligands

Kukoc-Modun¹,

Tsikas²,

Kraljević³

et al. 2017

Croat. Chem. Acta

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“…Both methods can be easily applied to the determination of NAC in pure form or in tablets. The proposed methods have several advantages over the previously reported kinetic spectrophotometric methods: 15,16 a wide linearity range of the calibration curve, sensitivity, selectivity, speed (5 min for the proposed fixed-time method in comparison to 30 min in Ref. 16) and straightforwardness (no need for additional catalytic effect, in contrast to Ref.…”

Section: Resultsmentioning

confidence: 99%

“…15,16 Also, none of the cited methods for the determination of NAC has used Fe 3+ and 2,4,6-trypyridyl-s-triazine (TPTZ) as a reagent solution. In this report, a novel, simple and sensitive kinetic spectrophotometric method with TPTZ as the chromogenic reagent for the determination of NAC is described and validated.…”

mentioning

confidence: 99%

Kinetic Spectrophotometric Determination of N-Acetyl-L-cysteine Based on a Coupled Redox-Complexation Reaction

Kukoc-Modun

Radić

2010

ANAL. SCI.

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Surprisingly, to the authors' knowledge, there are only two published kinetic spectrophotometric methods for the determination of NAC. 15,16 Also, none of the cited methods for the determination of NAC has used Fe 3+ and 2,4,6-trypyridyl-s-triazine (TPTZ) as a reagent solution. In this report, a novel, simple and sensitive kinetic spectrophotometric method with TPTZ as the chromogenic reagent for the determination of NAC is described and validated. Ease of application, sensitivity, short analysis time, low cost and reliability are its main advantages. The initial rate and fixed-time methods, after their optimization and validation, are adopted for the determination of NAC in its pharmaceutical formulations. Experimental ReagentsAll chemicals were of analytical-reagent grade, and solutions were prepared in Milli-Q deionized water.A stock solution of NAC, 1.0 × 10 -2 mol L -1 , was prepared by dissolving 163.2 mg of NAC (Merck, Darmstadt, Germany) in deionized water up to 100.0 mL in volume. The stock solution was stable for at least 30 days when it was stored in a dark bottle at 4 C. Working solutions of lower concentration were prepared daily by appropriate dilution of the stock solution with deionized water.A stock solution of Fe 3+ , 1.0 × 10 -2 mol L -1 , was prepared by dissolving 270.3 mg of FeCl3·6H2O (Kemika, Zagreb, Croatia) in a portion of deionized water. Concentrated hydrochloric acid (0.5 mL) was added to prevent the hydrolysis of iron, before making up to a volume of 100.0 mL.A stock solution of TPTZ (Merck, Germany), 1.0 × 10 -2 mol L -1 , was prepared by dissolving 312.3 mg in 2.0 mL of HCl (c (HCl) = 6.0 mol L -1 ), and diluted to 100.0 mL with deionized water. A stock solution of TPTZ was stored in a dark bottle at 4 C. A novel simple kinetic spectrophotometric method for the determination of N-acetyl-L-cysteine (NAC) has been developed and validated. The proposed method is based on a coupled redox-complexation reaction, the first step of which is the reduction of Fe 3+ by NAC; the second one includes the complexation of Fe 2+ , resulting from the preceding redox reaction, with 2,4,6-trypyridyl-s-triazine (TPTZ). The stable Fe(TPTZ)2 2+ complex exhibits an absorption maximum at λ = 593 nm. The initial rate and fixed-time (at 5 min) methods were utilized for constructing calibration graphs. The graphs were linear in concentration ranges from 4.0 × 10 -6 to 1.0 × 10 -4 mol L -1 for the initial rate method and 1.0 × 10 -6 to 1.0 × 10 -4 mol L -1 for the fixed-time method, with detection limits of 1.0 × 10 -6 and 1.7 × 10 -7 mol L -1 , respectively. The proposed methods were successfully applied for the determination of NAC in its commercial pharmaceutical formulations.

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