Talanta 76 (2008) 685–689 Contents lists available at ScienceDirect Talanta journal homepage: www.elsevier.com/locate/talanta Simultaneous square-wave voltammetric determination of aspartame and cyclamate using a boron-doped diamond electrode Roberta Antigo Medeiros, Adriana Evaristo de Carvalho, Romeu C. Rocha-Filho, Orlando Fatibello-Filho ∗ Departamento de Qu´ ımica, Universidade Federal de S˜ ao Carlos, C.P. 676, 13560-970 S˜ ao Carlos, SP, Brazil article info Article history: Received 5 February 2008 Received in revised form 8 April 2008 Accepted 9 April 2008 Available online 20 April 2008 Keywords: Aspartame Cyclamate Boron-doped diamond electrode Square-wave voltammetry abstract A simple and highly selective electrochemical method was developed for the simultaneous determination of aspartame and cyclamate in dietary products at a boron-doped diamond (BDD) electrode. In square- wave voltammetric (SWV) measurements, the BDD electrode was able to separate the oxidation peak potentials of aspartame and cyclamate present in binary mixtures by about 400 mV. The detection limit for aspartame in the presence of 3.0 × 10 -4 mol L -1 cyclamate was 4.7 × 10 -7 mol L -1 , and the detection limit for cyclamate in the presence of 1.0 × 10 -4 mol L -1 aspartame was 4.2 × 10 -6 mol L -1 . When simul- taneously changing the concentration of both aspartame and cyclamate in a 0.5 mol L -1 sulfuric acid solution, the corresponding detection limits were 3.5 × 10 -7 and 4.5 × 10 -6 mol L -1 , respectively. The rel- ative standard deviation (R.S.D.) obtained was 1.3% for the 1.0 × 10 -4 mol L -1 aspartame solution (n = 5) and 1.1% for the 3.0 × 10 -3 mol L -1 cyclamate solution. The proposed method was successfully applied in the determination of aspartame in several dietary products with results similar to those obtained using an HPLC method at 95% confidence level. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Aspartame and cyclamate are artificial sweeteners widely used in the food, beverage, confectionery and pharmaceutical industries throughout the world. Aspartame (N-l--aspartyl-l-phenylalanine methyl ester), shown in Fig. 1, was accidentally synthesized in 1965 using aspartic acid, phenylalanine and methanol as start reagents. It is a white, odorless, crystalline powder with sweetness potency 180–200 times that of sucrose [1–4]. Since its approval in 1981 for use as a low-calorie sweetener in dry food, the market has grown rapidly and today aspartame is one of the most frequently used artificial sweeteners [5–7]. Cyclamate (Fig. 1) was synthesized in 1937 at the University of Illinois (USA) by graduate student Michael Sveda, who by accident discovered the compound’s very sweet taste (potency 30 times that of sucrose). Although cyclamate is stabler than other sweeteners [2,7–9], it is no longer permitted as a food additive in many countries (e.g. Canada, USA, and several Euro- pean countries), due to its conversion to cyclohexylamine, which is a strong carcinogen [10]. However, the results of all the differ- ent studies carried out seeking to verify the toxicity of cyclamate reported few effects even when high amounts of the sweetener ∗ Corresponding author. Tel.: +55 16 33518098; fax: +55 16 33518350. E-mail address: bello@dq.ufscar.br (O. Fatibello-Filho). were ingested [11]. After evaluation of the available toxicological studies, the use of cyclamate in foods and drinks is considered safe, being allowed in countries such as Germany, Switzerland, Brazil, and South Africa [8]. In order to control their calorie intake, consumers select low- calorie foods. In these, a sweetener may be used by itself or in combination with sugars and other sweeteners, and the latter is becoming increasingly popular in recent years owing to technical, health and commercial advantages [12]. Thus, sweeteners can be found in a variety of foods such as carbonated soft drinks, gelatin dessert mixes, pudding mixes, chewing gums, and numerous other dietary products [2,4]. Many methods have been developed for analysis of individual sweeteners, but relatively few methods capable of simultane- ously analyzing several sweeteners have been reported. In recent years, the use of high performance liquid chromatography (HPLC) [5,11–19] has become the method of choice for aspartame and sodium cyclamate analysis because it is relatively simple while providing generally good qualitative and quantitative results for many types of samples. However, usually this method is costly and requires a lengthy pre-treatment of the sample prior to the chromatographic analysis. Electrochemical techniques can be alternative methods for aspartame and cyclamate determination because they are sim- ple, fast, and low cost. Various potentiometric or amperometric 0039-9140/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.talanta.2008.04.015