Abstract
The present work presents the development of a sensitive and selective amperometric sensor for the determination of hydrazine (HZ) in pharmaceutical formulations using a glassy carbon electrode (GCE) modified with a composite based on Co(Salophen), reduced graphene oxide (rGO) and deoxyribonucleic acid (DNA). The rGO/Co(Salophen)/DNA composite was characterized by using Fourier-transform infrared spectroscopy (FTIR), cyclic voltammetry, and amperometry. The proposed platform presented a well-defined voltammetric profile with a redox couple around 0.32 V vs. Ag/AgCl which showed excellent catalytic activity towards HZ oxidation. The peak current of HZ electrochemical oxidation on the proposed electrochemical platform have changed linearly with the HZ concentration in the range from 2 to 364 µmol L-1. The proposed platform presented sensitivity, limit of detection, and limit of quantification of 0.056 µA L µmol-1, 0.54 µmol L-1, and 1.64 µmol L-1 to HZ, respectively. The relative standard deviation for eight determinations using a solution of 50 µmol L-1 HZ was 0.85%. The proposed sensor was successfully applied for the determination of HZ in pharmaceutical formulations, and the recovery tests showed a good accuracy with recovery percentage between 99 and 101%.
Highlights
The graphite oxide had been reduced by hydrazine route, peaks at 1385 and 1110 cm−1 corresponding to the stretching vibration of C−C of carboxylic acid and C−OH of alcohol were observed in Fourier-transform infrared spectroscopy (FTIR) spectrum of rGO, justifying the hydrophilic nature of obtained reduced graphene oxide.[38]
In order to investigate the nature of the electrocatalytic oxidation of hydrazine on the rGO/Co(Salophen)/deoxyribonucleic acid (DNA) modified electrode, it was carried out cyclic voltammograms (CV) at several scan rates
In order to verify the selectivity of the proposed method, rGO/Co(Salophen)/DNA/glassy carbon electrode (GCE) was used for the determination of impurities of HZ that may be present in the isoniazid based drugs, investigating possible interferences of chemical species that are often found in the analyzed tablet samples
Summary
The interest on hydrazine (HZ) has been increasing due to its high reactivity, which has been exploited in the production of a number of materials including insecticides and pesticides, as well as it has been employed in the preparation of some pharmaceutical formulations such as nifuroxazide, carbidopa, hydralazine, dihydralazine, isoniazid and iproniazide.[1,2,3,4] On the other hand, the HZ is an extremely toxic compound as stated by some regulatory agencies such as the United States Environmental Protection Agency and the European Medicines Agency.[5,6]According to regulatory agencies, the recommended levels of HZ in medicinal products such as isoniazid based drugs is of 125 ppm[5,6] since the exposition to high levels of hydrazine can be harmful to human life because of its potential carcinogenic and mutagenic effects.[5,6,7] In this sense, the monitoring of HZ in pharmaceutical formulations is of high importance to ensure the quality of the medicines released for consumption by the population.The high importance of HZ in industrial, environmental and pharmaceutical fields have motivated the development of several analytical methodologies for HZ determination, such as spectrophotometry,[8] injection analysis based systems,[9] chromatographic methods,[10,11] and electrochemical methods.[12,13,14,15] The electrochemical methods present some interesting properties in comparison to the previously. The proposed rGO/Co(Salophen)/DNA/glassy carbon electrode (GCE) sensor presents low cost and can be applied for determination of HZ with high selectivity, precision, accuracy, and low response time.
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