Spectrophotometric determination of amines with p-chloranil

Smith, Robert E.; Davis, W.

doi:10.1021/ac00277a019

Cited by 39 publications

(20 citation statements)

References 37 publications

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“…A literatura descreve que o p-cloranil pode interagir com moléculas contendo centros doadores de elétrons segundo dois tipos de reações, sendo uma delas baseada na formação de uma aminoquinona mono-substituída (Esquema 1a) e a outra, através da formação de um complexo de transferência de carga com subseqüente dissociação do mesmo em solvente polar formando par iônico radicalar 21,23 (Esquema 1b). Com base nesse relato 21,23 e em testes qualitativos realizados em nosso laboratório supomos que a reação predominante entre citrato de sildenafil, e p-cloranil na presença de peróxido de hidrogênio consiste na formação de uma amino-quinona substituída.…”

Section: Resultsunclassified

“…Com base nesse relato 21,23 e em testes qualitativos realizados em nosso laboratório supomos que a reação predominante entre citrato de sildenafil, e p-cloranil na presença de peróxido de hidrogênio consiste na formação de uma amino-quinona substituída. Nesse caso, o peróxido provavelmente estaria atuando na oxidação do citrato de sildenafil que então reage com o p-cloranil formando o produto de substituição.…”

Section: Resultsunclassified

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Determinação espectrofotométrica de citrato de sildenafil em formulações farmacêuticas

Weinert¹,

Pezza²,

Pezza³

2008

Quím. Nova

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Recebido em 25/5/07; aceito em 11/10/07; publicado na web em 2/4/08 SPECTROPHOTOMETRIC DETERMINATION OF SILDENAFIL CITRATE IN PHARMACEUTICAL FORMULATIONS. This paper describes a simple and rapid spectrophotometric method for quantitative determination of sildenafil citrate based on its reaction with p-chloranil accelerated by hydrogen peroxide, producing a stable purple compound (λ max = 535 nm). In the absence of peroxide this reaction is very slow. The experimental conditions were optimized by using response surface methodologies. Beer's law is obeyed in a concentration range of 8.52 x 10 -5 -1.70 x 10 -3 mol L -1 (r = 0.999). The detection limit was 1.96 x 10 -5 mol L -1. The method was successfully applied for the determination of sildenafil citrate in medicines with good accuracy and precision.

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Section: Resultsunclassified

Determinação espectrofotométrica de citrato de sildenafil em formulações farmacêuticas

Weinert¹,

Pezza²,

Pezza³

2008

Quím. Nova

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“…33,34 Spectrophotometric methods based on these interactions are usually simple and convenient because of the rapid formation of complexes. [34][35][36][37] Azithromycin (electron donor) reacts instantaneously with p-chloranil (p-acceptor) in the presence of hydrogen peroxide, resulting in the formation of an intense purple-red product at room temperature, which exhibits an absorption maximum at 540 nm. This reaction is markedly accelerated by hydrogen peroxide; however, without hydrogen peroxide, the reaction is very slow at room temperature.…”

Section: Resultsmentioning

confidence: 99%

Flow-Injection Spectrophotometric Determination of Azithromycin in Pharmaceutical Formulations Using p-Chloranil in the Presence of Hydrogen Peroxide

Rufino

Pezza

2008

ANAL. SCI.

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A flow-injection (FI) spectrophotometric procedure exploiting merging zones is proposed for the determination of azithromycin in pharmaceutical formulations. The method is based on the reaction of azithromycin with tetrachloro-pbenzoquinone (p-chloranil) accelerated by hydrogen peroxide and conducted in a methanol medium, producing a purplered color compound (lmax = 540 nm). The FI system and the experimental conditions were optimized using a multivariate method. Beer's law is obeyed in a concentration range of 50 -1600 mg mL -1 with an excellent correlation coefficient (r = 0.9998). The detection limit and the quantification limit were 6.6 and 22.1 mg mL -1 , respectively. No interference was observed from the common excipients, and the recoveries were within 98.6 to 100.4%. The procedure was applied to the determination of azithromycin in pharmaceuticals with a high sampling rate (65 samples h -1 ). The results obtained by the proposed method were in good agreement with those obtained by the comparative method at 95% confidence level.

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“…Charge-transfer complexation reactions have been extensively applied to the spectrophotometric determination of several important drugs such as methyldopa [9], fluoxetine [10], sertraline [11], famotidine [12], perindopril [13], and some β -adrenergic blocking agents [14]. Amines are excellent electron donors and can strongly interact with electron acceptors.…”

Section: Resultsmentioning

confidence: 99%

10.1007/s10809-008-3009-9

2000

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The present paper describes an effective and low-cost spectrophotometric method for the determination of mefenamic acid in its pure form and pharmaceutical preparations. The method is based on the chargetransfer complexation between mefenamic acid as an n -electron donor and chloranil as a π -acceptor to form a violet chromogen measured at 540 nm. Under the optimum conditions, a linear relationship with a good correlation coefficient (0.9996) was found between the absorbance and concentration of the studied drug in the range of 10-60 µ g/mL. The optimal reaction conditions such as reagent concentration, heating time, and stability of the reaction product were determined. The limit of detection (LOD) was 2.16 µ g/mL and the limit of quantification (LOQ) was 7.15 µ g/mL. The method was successfully applied to the determination of mefenamic acid in pharmaceutical preparations without any interference from common excipients.

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Spectrophotometric determination of amines with p-chloranil

Cited by 39 publications

References 37 publications

Determinação espectrofotométrica de citrato de sildenafil em formulações farmacêuticas

Determinação espectrofotométrica de citrato de sildenafil em formulações farmacêuticas

Flow-Injection Spectrophotometric Determination of Azithromycin in Pharmaceutical Formulations Using p-Chloranil in the Presence of Hydrogen Peroxide

10.1007/s10809-008-3009-9

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