Electrochimica Acta 116 (2014) 326–333 Contents lists available at ScienceDirect Electrochimica Acta jou rn al hom ep age: www.elsevier.com/locate/elec tacta Electrochemical characterization and determination of paclitaxel drug using graphite pencil electrode Jayant I. Gowda, Sharanappa T. Nandibewoor ∗ P.G. Department of Studies in Chemistry, Karnatak University, Dharwad-580 003, India a r t i c l e i n f o Article history: Received 28 August 2013 Received in revised form 9 October 2013 Accepted 3 November 2013 Available online 15 November 2013 Keywords: Paclitaxel Graphite pencil electrode Voltammetry Human biological fluids a b s t r a c t Paclitaxel, an anticancer drug was electrochemically studied in phosphate buffer at different pH using graphite pencil electrode. For analytical purpose, a well resolved irreversible diffusion controlled voltam- metric peak was obtained in pH 7 phosphate buffer solution of ionic strength 0.2 M at 1.214 V for cyclic voltammetry. According to the linear relationship between the peak current and the paclitaxel concentration, differential pulse voltammetric method was developed for its quantitative determina- tion in pharmaceuticals and human biological fluids. The linear response was obtained in the range of 4.0 × 10 -7 to 3.0 × 10 -6 M with a detection limit of 2.46 × 10 -9 M. Precision and accuracy of the devel- oped method was checked by recovery studies. The proposed method was successfully applied to the individual injection dosage form and human biological fluids. © 2013 Elsevier Ltd. All rights reserved. 1. Introduction The development of a simple, sensitive, rapid and reliable method for the determination of drugs is of great importance. The graphite pencil electrode (GPE) has been successfully used as a biosensor in modern electroanalytical field due to its high electrochemical reactivity, good mechanical rigidity, low cost, low technology and ease of modification, renewal and low background current [1,2]. The GPE has good application in the analysis of neu- rotransmitter and detection of traces of metal ions and drugs. Paclitaxel (PAC, chemical structure as given in Scheme 1) is a mitotic inhibitor used in cancer chemotherapy. Paclitaxel is one of several cytoskeletal drugs that target tubulin. Paclitaxel-treated cells have defects in mitotic spindle assembly, chromosome seg- regation, and cell division. Unlike other tubulin-targeting drugs such as colchicine that inhibit microtubule assembly, paclitaxel stabilizes the microtubule polymer and protects it from disas- sembly. Chromosomes are thus unable to achieve a metaphase spindle configuration. This blocks progression of mitosis, and pro- longed activation of the mitotic checkpoint triggers apoptosis or reversion to the G-phase of the cell cycle without cell division [3,4]. Paclitaxel is approved for ovarian, breast and lung cancers and Kaposi’s sarcoma [5]. It is recommended in NICE guidance of June ∗ Corresponding author. Tel.: +91 836 2215286; fax: +91 836 2747884. E-mail address: stnandibewoor@yahoo.com (S.T. Nandibewoor). 2001 that it should be used for nonsmall cell lung cancer in patients unsuitable for curative treatment, and in first-line and second-line treatment of ovarian cancer and it should be available for the treat- ment of advanced breast cancer after the failure of anthracyclic chemotherapy. Different voltammetric methods have been reported for the determination of paclitaxel, including square wave voltammetry at Cysteamine/DNA/SWNTs-Film modified Au electrode [6] and cathodic stripping voltammetry at mercury drop electrode [7]. Above mentioned voltammetric methods are not as good as our method, since in the previous method Cysteamine/DNA/SWNTs modified electrode expensive chemicals are used and the mod- ification is not easy, in another method mercury drop electrode main draw backs are poisonous nature of mercury and variable sur- face area of mercury drop electrode. The other chromatographic methods reported for the determination of PAC are liquid chro- matography with anodic amperometric detection [8] and different HPLC methods [9–13]. The main problems encountered in using such methods are time consuming extraction and separation pro- cedure. Survey of literature revealed that no electroanalytical meth- ods for determination of paclitaxel by using GPE was reported. The aims of this study are to establish the experimental condi- tions, to investigate the oxidation mechanism of paclitaxel and to optimize the conditions for the determination of this compound in pharmaceutical dosage form and in human biological fluids using cyclic, linear sweep and differential pulse voltammetric tech- niques. 0013-4686/$ – see front matter © 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.electacta.2013.11.014