Voltammetric approach for pharmaceutical samples analysis; simultaneous quantitative determination of resorcinol and hydroquinone

A simple and precise analytical approach developed for single and simultaneous determination of resorcinol (RC) and hydroquinone (HQ) in pharmaceutical samples using carbon paste electrode (CPE) modified with 1-Ethyl-3-methylimidazolium tetrafluoroborate as ionic liquid and ZnFe2O4 nanoparticle. A significant enhancement in the peak current and sensitivity of the proposed sensor observed by using modifiers in the composition of working electrode compared to bare CPE which is in accordance with the results obtained from electrochemical impedance spectroscopy investigations. Electrochemical investigations revealed a well-defined irreversible oxidation peak for RC over a wide concentration range from 3.0 mu M to 500 mu M in 0.1 M phosphate buffer solution (pH 6.0) with the linear regression equations of I-p (mu A) = 0.0276 C-RC (mu M) + 0.5508 (R-2 = 0.997). The limit of detection and quantification for RC analysis were found to be 1.46 mu M and 4.88 mu M, respectively. However, the obtained SW voltammograms for simultaneous determination of RC and HQ exhibited a desirable peak separation of about 360 mV potential difference and a satisfactory linear response over the range of 50-700 mu M and 5-350 mu M with the favorable correlation coefficient of 0.991 and 0.995, respectively. The diffusion coefficient (D) of RC and the electron transfer coefficient (alpha) at the surface of ZnFe2O4/NPs/IL/CPE estimated to be 2.83 x 10(- 4) cm s(- 1) and 0.76. The proposed sensor as a promising and low-cost method successfully applied for determination of RC in commercial pharmaceutical formulations such as the resorcinol cream of 2% O/W emulsion available on the market with the recovery of 98.47 +/- 0.04.

Automated summary

A simple and precise analytical method has been developed for the determination of resorcinol and hydroquinone in pharmaceutical samples using carbon paste electrode modified with ionic liquid and nanoparticles. The method shows promising potential in pharmaceutical analysis.