Voltammetric Determination of Adrenaline Using a Poly(1-Methylpyrrole) Modified Glassy Carbon Electrode Mehmet Aslanoglu,* Aysegul Kutluay, Serpil Karabulut and Sultan Abbasoglu Department of Chemistry, University of Harran, Sanliurfa 63510, Turkey A voltammetric method using a poly(1-methylpyrrole) modified glassy carbon electrode was devel- oped for the quantification of adrenaline. The modified electrode exhibited stable and sensitive current re- sponses towards adrenaline. Compared with a bare GCE, the modified electrode exhibits a remarkable shift of the oxidation potentials of adrenaline in the cathodic direction and a drastic enhancement of the anodic current response. The separation between anodic and cathodic peak potentials (DEp) for adrenaline is 30 mV in 0.1 M phosphate buffer solution (PBS) at pH 4.0 at modified glassy carbon electrodes. The lin- ear current response was obtained in the range of 7.5 ´ 10 -7 to 2.0 ´ 10 -4 M with a detection limit of 1.68 ´ 10 -7 M for adrenaline by square wave voltammetry. The poly(1-methypyrrole)/GCE was also effective to simultaneously determine adrenaline, ascorbic acid and uric acid in a mixture and resolved the overlap- ping anodic peaks of these three species into three well-defined voltammetric peaks in cyclic voltam- metry. The modified electrode has been successfully applied for the determination of adrenaline in pharmaceuticals. The proposed method showed excellent stability and reproducibility. Keywords: Modified electrodes; 1-Methylpyrrole; Adrenaline; Ascorbic acid; Uric acid. INTRODUCTION Adrenaline, a sympathomimetic drug, is widely used for the treatment of hypertension, cardiac arrest, myocar- dial infarction and cardiac surgery in clinics. 1 It is a chemi- cal mediator for conveying the nerve pulse to efferent or- gans. Adrenaline is also used to stimulate heartbeat and to treat emphysema, bronchitis, bronchial asthma and other allergic conditions, as well as in the treatment of the eye disease, glaucoma. 2 Therefore, sensitive determination of adrenaline has an important significance to medicine and life science. Several methods have been reported for the de- termination of adrenaline such as high performance liquid chromatography, 3-5 fluorometry, 6-8 chemiluminescence, 9,10 capillary electrophoresis 11 and spectrophotometry. 12 How- ever, such methods are quite complicated since some of these methods need derivatization or combination with various detection methods. They also have low sensitivity and specificity. Electrochemical methods have been useful for the de- termination of electroactive species in pharmaceuticals and body fluids due to their simplicity and low cost. However, in electrochemical detection of adrenaline, voltammetric methods may suffer from low sensitivity and selectivity that leads to an inactive overpotential due to the irrevers- ibility of its voltammetric behavior. 1 Another problem in monitoring adrenaline with electrochemical methods is the coexistence of ascorbic acid and uric acid. The presence of ascorbic acid and uric acid with adrenaline possessing oxi- dation peak potentials close to those of adrenaline results in the voltammetric response of adrenaline being almost over- lapped by that of ascorbic acid or uric acid at conventional electrodes. A number of articles have appeared in the litera- ture regarding these problems. 13-17 In these articles, electro- chemically modified electrodes show good electrocatalytic activity and stability towards the detection of electroactive species. 18-20 Poly(osmium oxide/hexacyanoruthenate) film is a good example of the determination of adrenaline which shows electrocatalytic activity for monitoring adrenaline. 21 Yao et al. also described a poly(erichrome black T) film- modified GCE, which exhibited good activity for the detec- tion of adrenaline. 1 In this study, we report cyclic voltam- metric behaviour of adrenaline at a bare and a poly(1-meth- ylpyrrole) modified GCE. The modified electrode was found to be electrocatalytically active towards the oxida- tion of adrenaline. Furthermore, it has been shown that the oxidation peak potential of adrenaline could be well sepa- 794 Journal of the Chinese Chemical Society, 2008, 55, 794-800 * Corresponding author. Tel: +90-4143440020 ext. 1264; E-mail: maslanoglu@harran.edu.tr