Journal of Pharmaceutical and Biomedical Analysis 26 (2001) 873–881 Electroanalysis of dapsone, an anti-leprotic drug P. Manisankar *, A. Sarpudeen, S. Viswanathan Department of Industrial Chemistry, Alagappa Uniersity, Karaikudi -630 003, India Received 24 November 2000; received in revised form 4 April 2001; accepted 15 April 2001 Abstract The electrochemical oxidation and adsorption of dapsone, an anti-leprotic drug were studied in aqueous alcohol medium at a stationary glassy carbon electrode. Cyclic voltammetry studies showed one well-defined oxidation peak in the potential range 1.2–1.9 V at pH conditions 1.0, 4.0, 7.0, 9.2 and 13.0. The oxidation was irreversible and exhibited diffusion controlled adsorption. Controlled potential coulometry revealed one electron oxidation of the amino group in the molecule. A systematic study of the experimental parameters that affect the squarewave stripping response was carried out and the optimized experimental conditions were arrived at. A calibration plot was derived for the determination of the compound in solution. This method was used for the determination of dapsone in tablets and urine. The limits of determination was 0.0036 and 3.56 mg/ml and the relative standard deviation (n =10) was 4 ppt (0.4%) at a concentration level 0.100 mg/ml. © 2001 Elsevier Science B.V. All rights reserved. Keywords: Dapsone; Cyclic voltammetry; Squarewave voltammetry; Tablets; Urine www.elsevier.com/locate/jpba 1. Introduction Dapsone, 4,4-diamino-biphenyl-sulphone (DDS) is one of the most important and main drug available for the treatment of leprosy [1]. It is also used in the treatment of malarial diseases and as an anti-inflammatory [2] in acute ileitis. Dapsone with clofazimine prevents the inhibitory effect on neutrophil motility [3]. With ethambutol and ri- fampin it is used for the treatment of human eye disease [4]. The structural formula of dapsone is: Perusal of literature reveals the availability of methods like HPLC [5,6], LC [7], spectrophoto- metry and polarography for the determination of DDS in tablets, blood and urine [1–11]. The cleavage of DDS using a mercury cathode and tetraalkyl ammonium salts in both protic and aprotic media has also been reported [12]. A number of procedures were available for the de- termination of dapsone using HPLC technique. HPLC, at its current stage of development, is clearly not a method for analytical problems with a high repetition rate because the receptive condi- tion of the system requires 24–36 h. On the other hand, electroanalysis is a manageable method, which is suitable for various problems [13]. Hence the development of electrochemical determination * Corresponding author. Fax: +91-4565425-202. E-mail address: pms11@rediffmail.com (P. Manisankar). 0731-7085/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved. PII:S0731-7085(01)00480-0