Studies of zinc(II) in pharmaceutical and biological samples by extractive spectrophotometry: using pyridoxal-4-phenyl-3-thiosemicarbazone as chelating reagent

Abstract

Piridoxal-4-fenil-3-tiossemicarbazona (PPT) é proposto como um novo reagente sensível para a determinação espectrofotométrica de zinco(II). PPT reage com zinco(II) no intervalo de pH entre 5,0 e 6,0, para formar um complexo colorido amarelo, o qual foi adequadamente extraído em n-butanol. A absorbância do complexo Zn(II)-PPT foi medida em diferentes intervalos de tempo, a 430 nm, para averiguar a estabilidade do complexo. Foi observado que o desenvolvimento da cor foi instantâneo e estável por mais de 48 h. O sistema obedece a lei de Beer até 6,0 μg mL -1 de zinco(II), com uma excelente linearidade em termos do valor do coeficiente de correlação, de 0,999. A absortividade molar e sensitividade de Sandell da espécie extraída é 1,6 × 10 4 L mol -1 cm -1 e 4,085 × 10 -3 μg cm -2 , respectivamente, a 430 nm. O limite de detecção do método é 0,04 μg mL -1 . Para avaliar a precisão do método, determinações foram efetuadas em diferentes concentrações; o desvio padrão relativo não excedeu 3,1%. A composição do complexo de zinco(II) com PPT foi estudada pelos métodos de variação contínua de Job, da razão molar, método de Asmus e da razão da inclinação. PPT tem sido empregado satisfatoriamente para a determinação de zinco(II) isoladamente, ou na presença de outros íons, normalmente associados ao zinco(II) em amostras farmacêuticas e biológicas. Vários materiais de referência (NIST 1573, NBS 1572 e NIST SRM 8435) têm sido testados para a determinação de zinco, com o propósito de avaliar a exatidão do presente método. Os resultados do método proposto são concordantes com os obtidos por espectrometria de absorção atômica com chama.Pyridoxal-4-phenyl-3-thiosemicarbazone (PPT) is proposed as a new sensitive reagent for the sensitive extractive spectrophotometric determination of zinc(II). PPT reacts with zinc(II) in the pH range 5.0-6.0 to form a yellow colored complex, which was well extracted into n-butanol. The absorbance value of Zn(II)-PPT complex was measured at different intervals of time at 430 nm, to ascertain the stability of the complex. It was observed that the color development was instantaneous and stable for more than 48 h. The system obeyed Beer's law up to 6.0 μg mL -1 of zinc(II), with an excellent linearity in terms of correlation coefficient value of 0.999. The molar absorptivity and Sandell's sensitivity of the extracted species is 1.6 × 10 4 L mol -1 cm -1 and 4.085 × 10 -3 μg cm -2 at 430 nm. The detection limit of the method is 0.04 μg mL -1 . To assess precision of the method, determinations were carried out at different concentrations; the relative standard deviation does not exceed 3.1%. The composition of the zinc(II) complex with PPT was studied by the method of Job's continuous variation, molar ratio method, Asmus' method and slope ratio method. It has been satisfactorily applied for the determination of zinc(II), when present alone or in presence of diverse ions, which are usually associated with zinc(II) in pharmaceutical and biological samples. Various certified reference materials (NIST 1573, ...

Chemical composition of wonderful kola (Bucchlozia coriacea) and breadfruit (Artocarpus altilis) seeds grown in south–south, Nigeria

“…Zinc is an essential element for all animals including human beings and it plays an important physiological role. Zinc is also associated with many enzymes system, both as metallo-enzyme and enzymes activator (Sarma, 2006). Over 100 zinc metallo-enzymes have been described to date, including a number of regulatory proteins and both RNA and DNA polymerase (Delvin, 1992).…”

Solvent Extraction Studies on Copper(II) and Silver(I) Complexes of Bis(4-hydroxypent-2-ylidene)diaminoethane: Composition of Extracted Copper(II) Species

“…Job's continuous variation or equimolar method was employed in determining the composition of extracted species as reported elsewhere 16 and confirmed by the method of equilibration constant 17 .…”

Spectrophotometric Study of a new Complexation between Zn(II) and 5-Bromosalicylaldehyde Thiosemicarbazone and Its Application

“…Zn(II) forms a chelate complex with many reagents such as thiosemicarbazones. Some representative examples are benzildithiosemicarbazone [13], di-2-pyridyl ketone salicyloylhydrazone [14], 2,4-dihydroxybenzaldehyde isonicotinoyl hydrazone [15], pyridoxal-4-phenyl-3thiosemicarbazone [16], N-ethyl-3carbazolecarboxaldehyde-3-thiosemicarbazone [17], di-2-pyridyl ketone benzoylhydrazone [18], bis-[2,6-(2′-hydroxy-4′-sulpho-1′-napthylazo)]pyridine disodium salt [19], and 5,7-dibromo-8hydroxyquinoline [20], salicylaldehyde thiosemicarcbazone [21]. In recent years, the complexation of 5-bromosalicylaldehyde thiosemicarbazone (5-BSAT) reagent with some metallic ions has been reported.…”