Journal of The Electrochemical Society, 161 (4) H189-H194 (2014) H189 0013-4651/2014/161(4)/H189/6/$31.00 © The Electrochemical Society A Graphene-Polyaniline-Bi 2 O 3 Hybrid Film Sensor for Voltammetric Quantification of Anti-Inflammatory Drug Etodolac Rajeev Jain z and Swati Shrivastava School of Studies in Chemistry, Jiwaji University, Gwalior-474011, India A highly sensitive and stable Graphene-Polyaniline-Bi 2 O 3 (Grp-Pani-Bi 2 O 3 ) composite film modified glassy carbon sensor was fabricated for electrochemical sensing of anti-inflammatory drug etodolac (ETD). The morphology was characterized by scanning electron microscopy and the electrochemical performance of the fabricated sensor was assessed by square wave and cyclic voltam- metry. The influence of various parameters such as pH, effect of scan rate, and loading of Grp-Pani-Bi 2 O 3 composite at GCE on analytical performance of the developed sensor was investigated. The excellent electrocatalytic activity of developed sensor results in good characteristics such as low potential detection of ETD, good stability, fast response, and anti-interferent ability. Oxidation peak current was linear over the target concentration with correlation coefficient of 0.9938. The limit of detection (LOD) and limit of quantification (LOQ) are 10.03 ng mL −1 and 30.08 ng mL −1 respectively. The proposed method was successfully applied to the determination of ETD in pharmaceutical formulation. The ease of fabrication, excellent electrochemical performance and high electroactive surface area are the promising features of the fabricated sensor. © 2014 The Electrochemical Society. [DOI: 10.1149/2.043404jes] All rights reserved. Manuscript submitted January 7, 2014; revised manuscript received January 30, 2014. Published February 6, 2014. Chemically modified electrodes are an important subject of re- search due to their significant advantages, such as excellent sensitiv- ity, simplicity, rapid response, low cost and the ability to provide material properties that are acceptable to many electrochemical applications. 1–12 Various nanomaterials such as graphene, carbon nan- otubes and metal oxide nanomaterials 13–18 are attractive electrode ma- terials and have been widely used to modify electrodes in order to enhance the sensitivity and selectivity of the electrochemical sensor. As a promising candidate in many applications conducting poly- mer, polyaniline (PANI) have been increasingly used for vari- ous electrochemical sensors due to its relatively high conductivity, low cost, facile synthesis, biocompatible nature and environmental resistance. 19–22 On the other hand, graphene has been recognized as one of the most promising electrode material and is known to show excellent electronic properties, large surface-to-volume ratio, high conductivity, small band gap. 23–28 Likewise, bismuth oxide is an en- vironmentally friendly compound, with very low toxicity and is also known to be an important metal oxide due to its characteristic pa- rameters such as energy band gap, large surface area, electrochem- ical stability and photoconductivity that are suitable for large range applications. 29–32 On the basis of the above understanding, the combi- nation of graphene with conducting Pani-Bi 2 O 3 nanocomposite seems to be a promising attempt to have a possible synergic effect to improve the performances of sensor. Etodolac (Scheme I) [1,8-diethyl-1,3,4,9-tetrahydropyrano(3, 4-b)-indole-1-acetic acid] (ETD) is a member of non-steroidal anti-inflammatory drugs that selectively inhibits the activity of prostaglandin synthetase and also used in postoperative pain and rheumatoid arthritis. It is rapidly metabolized in the liver, followed by renal elimination as the primary route of excretion. 33 Various analyti- cal methods have been reported for the quantitation of ETD in different matrices (viz. pharmaceutical formulations, plasma and urine). These methods include high performance liquid chromatography (HPLC) with UV detection, 34–38 hydrophilic interaction liquid chromatogra- phy (HILIC) with tandem mass spectrometry (MS/MS), 39 spectropho- tometry and spectrofluorimetry, 40 and capillary electrophoresis. 41 Most of the previously reported methods are time consuming, require sophisticated instrumentation and extraction of the drug from its formulations and/or biological fluids prior to the analysis which limit their use in quality control laboratories. Voltammetric methods are highly-sensitive, convenient and effective tool for the analysis of pharmaceuticals and biomolecules 42–52 owing to their simplicity, low cost and relatively short time analysis. However, there is no systematic report available on the study of electrochemical oxidation of ETD at Graphene-Polyaniline-Bi 2 O 3 (Grp-Pani-Bi 2 O 3 ) hybrid film sensor. In z E-mail: rajeevjain54@yahoo.co.in the present voltammetric method the detection limit is found to be at the nanogram level and makes it more sensitive than already reported methods. In the present study, Graphene-Polyaniline-Bi 2 O 3 (Grp-Pani- Bi 2 O 3 ) composite film modified glassy carbon sensor was prepared and used for the detection of etodolac in pharmaceutical formula- tion. Further, the sensitivity of developed sensor was compared with the four electrodes i.e. glassy carbon (GC), bismuth oxide modi- fied (Bi 2 O 3 /GCE), PANI modified (Pani/GCE), graphene modified (Grp/GCE) electrodes for etodolac detection. The results showed that hybrid film of Graphene-Polyaniline-Bi 2 O 3 (Grp-Pani-Bi 2 O 3 ) is more sensitive as compared to bare GCE, Bi 2 O 3 /GCE, Pani/GCE, Grp/GCE. Experimental Chemicals and reagents.— Bi 2 O 3 (99.8% purity) nanopowder (90–210 nm) was procured from Sigma Aldrich, USA. Graphene (12 nm) was procured from Graphene Laboratories, USA. All other chemicals used were of analytical reagent grade. Aniline was dis- tilled under reduced pressure prior to use and other reagents were employed without further purification. Etodolac (99% purity) was ob- tained from Cadila Pharmaceuticals Ltd., (India) and used as received. Tablets containing etodolac (Etogesic) labeled 400 mg were obtained from commercial sources. KCl (1.0 mol/L) solution was prepared in double distilled water and used as supporting electrolyte. A stock so- lution of ETD (1.0 mg mL −1 ) was prepared in methanol. The solutions for recording voltammograms were prepared by mixing appropriate volumes of stock solution, buffers and 1.0 mol/L KCl. All chemicals were procured at Jiwaji University, Gwalior (M.P.), India. Apparatus and measurements.— Electrochemical measurements were performed using a μ AUTOLAB TYPE III (Eco-Chemie B.V., Utrecht, The Netherlands) potentiostat–galvanostat with 757VA com- putrace software. The Grp-Pani-Bi 2 O 3 /GCE was used as working electrode, Ag/AgCl as reference electrode and graphite as auxiliary electrode. All the solutions examined by electrochemical techniques N H O C H 3 OH CH 3 O Scheme I. Chemical structure of etodolac. ecsdl.org/site/terms_use address. Redistribution subject to ECS license or copyright; see 117.217.92.204 Downloaded on 2014-02-18 to IP