A novel potentiometric naproxenate ion sensor immobilized in a graphite matrix for determination of naproxen in pharmaceuticals

Abstract

As características, o desempenho e a aplicação de um eletrodo do tipo Pt⎪Hg⎪Hg 2 (NAP) 2 ⎪ Graphite, onde NAP=íon naproxenato, são descritas. O eletrodo responde a NAP com sensibilidade de (58,1± 0,9) mV década -1 no intervalo de 5,0 × 10 -5 -1,0 × 10 -2 mol L -1 , a pH 6,0-9,0 e com um limite de detecção de 3,9 × 10 -5 mol L -1 . O eletrodo é de baixo custo e facilmente construído, apresenta um rápido tempo de resposta (10-35 s) e pode ser usado por um período de seis meses sem qualquer divergência considerável nos potenciais. O sensor supracitado mostrou boa seletividade para naproxeno na presença de várias substâncias, tais como carboxilatos e ânions inorgânicos, sendo aplicado na análise direta de naproxeno em medicamentos (comprimidos) via método da adição de padrão. Os resultados analíticos obtidos com o eletrodo proposto estão em boa concordância com aqueles obtidos pelo procedimento preconizado na Farmacopéia Americana.The characteristics, performance, and application of an electrode, namely, Pt⎪Hg⎪Hg 2 (NAP) 2 ⎪ Graphite, where NAP stands for naproxenate ion, are described. This electrode responds to NAP with sensivity of (58.1± 0.9) mV decade -1 over the range 5.0 × 10 -5 -1.0 × 10 -2 mol L -1 at pH 6.0-9.0 and a detection limit of 3.9 × 10 -5 mol L -1 . The electrode is easily constructed at a relatively low cost with fast response time (within 10-35 s) and can be used for a period of 6 months without any considerable divergence in potentials. The proposed sensor displayed good selectivity for naproxen in the presence of several substances, especially concerning carboxylate and inorganic anions. It was used for the direct assay of naproxen in commercial tablets by means of the standard additions method. The analytical results obtained by using this electrode are in good agreement with those given by the United States Pharmacopeia procedure.Keywords: naproxenate-sensitive electrode, potentiometry, pharmaceutical formulations Introduction Naproxen [(+)-2-(6-metoxy-2naphthyl)propionic acid], is a non-steroidal anti-inflammatory drug that also presents analgesic and antipyretic properties often preferred to acetylsalicylic acid because of its better absortion following oral administration and fewer adverse effects.Naproxen is extensively used in the treatment of many diseases like rheumatoid arthrits, degenerative joint disease, ankylosing spondylits, acute gout and primary dismenorrea. 1 Like other non-steroidal anti-inflammatory drugs, it inhibits the biosyntesis of prostaglandins. 1 The United States Pharmacopeia 2 2003 reports an highperformance liquid chromatography (HPLC) method for the determination of naproxen tablets. Several analytical methods have been reported for the determination of naproxen in pharmaceutical preparations including UV-visible spectrophotomery, 3-5 spectrofluorimetry, 6-8 room temperature phosphorimetry, 9,10 voltametry, 11 high-performance liquid chromatography, 12-14 capillary electrophoresis, 15,16 coulometry 17 and oscilometric titration. 18 However, most of these techniq...

Preparation and study of a naproxen ion-selective electrode

“…The other electrodes achieved the following lifetime: electrode DOA 15 months, electrode DIBP 19 months, electrode o-NPOE 18 months, and electrode DOS 19 months, respectively. This research proved the basic, analytical parameters of all electrodes (proposed work and [15][16][17][18]). Lifetime of these sensors amounted to six months.…”

“…The investigated electrodes [15][16][17][18] exhibited an operative lifetime of only 1.5-6 months, but the novel presented electrode (DBP) achieved a much longer lifetime of 20 months. This may be due to a different structure of quaternary ammonium salt, its increased lipophilicity and hence a longer time of elution of the complex ion pair from the polymer membrane (the electrodes were stored in air).…”

“…On the basis of the literature, there are limited scientific works on the use of ion-selective electrodes for naproxen determination [15][16][17][18]. These electrodes have different constructions: the electrode [15] with liquid membrane type, based on the use of tetraheptylammonium naproxenate, the electrode with polymeric membrane type with methyltrioctylammonium naproxenate [16], the electrode with graphite membrane based on mercury(I) naproxenate [17], and electrodes based on other quaternary ammonium salt in chloride and bromide forms with inner solution of naproxenate in NaCl solution [18].…”

Properties of naproxen ion-selective electrodes

“…The construction of the sensor has the advantages of simplicity and rapidity (the time of construction of the electrode is much shorter than the time of construction of solid contact electrodes [17,19] or liquid contact electrodes [18]. The naproxen electrode was characterized by good analytical parameters, i.e., a relatively short response time of 11s, near Nernstian response of the characteristic, and good selectivity over a number of organic and inorganic anions.…”

“…Only three papers describing naproxen ionselective electrodes, based on methyltrioctylammonium 6-methoxy-α-methyl-2-naphthalene acetate [17], tetraheptylammonium 6-methoxy-α-methyl-2-naphthalene acetate [18] and mercury (I) naproxenate [19], are published in the literature. These electrodes are characterized by similar, appropriate, analytical parameters, but sample preparation for their use is complicated and requires considerable time.…”