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The independent determination of two beta-blocker agents, namely propranolol (PROP) and atenolol (ATN), in pharmaceutical formulations using square-wave voltammetry and a cathodically pretreated boron-doped diamond electrode is described. These electroanalytical determinations of propranolol or atenolol were carried out in 0.1molL(-1) H(2)SO(4) or 0.5molL(-1) NaNO(3) (pH 1.0, adjusted with concentrated HNO(3)), respectively. Excellent linear calibration curves, ranging from 0.20 to 9.0micromolL(-1) for PROP and from 2.0 to 41micromolL(-1) for ATN, with detection limits of 0.18 and 0.93micromolL(-1), respectively, were obtained. The obtained recoveries range from 93.9% to 105.0%, for PROP, and from 92.5% to 106.0%, for ATN. The proposed method was successfully applied in the determination of both beta-blockers in several pharmaceutical formulations (tablets), with results in close agreement at a 95% confidence level with those obtained using official spectrophotometric methods.

A method for simultaneous determination of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) in food was developed that uses multiple pulse amperometry (MPA) with flow injection analysis (FIA). Determination of these phenolic antioxidants was carried out with a cathodically pretreated boron-doped diamond electrode and an aqueous ethanolic (30% ethanol, v/v) 10 mmol L⁻¹ KNO₃ solution (pH(cond) = 1.5) as supporting electrolyte. A dual-potential waveform, at E(det1) = 850 mV/200 ms and E(det2) = 1150 mV/200 ms versus Ag/AgCl (3.0 mol L⁻¹ KCl), was employed. The use of E(det1) or E(det2) caused the oxidation of BHA or of BHA and BHT, respectively; hence, concentration subtraction could be used to determine both species. The respective analytical curves presented good linearity in the investigated concentration range (0.050-3.0 μmol L⁻¹ for BHA and 0.70-70 μmol L⁻¹ for BHT), and the detection limits were 0.030 μmol L⁻¹ for BHA and 0.40 μmol L⁻¹ for BHT. The proposed method, which is simple, quick, and presents good precision and accuracy, was successfully applied in the simultaneous determination of BHA and BHT in commercial mayonnaise samples, with results similar to those obtained by HPLC, at a 95% confidence level.

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The several outstanding properties of boron‐doped diamond electrodes (BDDEs) have allowed their application for various purposes, among them electrochemical sensing. However, the electrochemical response of many redox species on BDDEs can be strongly dependent on whether their surfaces are predominantly hydrogen‐ (HT) or oxygen‐terminated (OT). Fortuitously, electrochemical pretreatments themselves can be used to enrich in situ the BDEE surface in one or the other type of termination. The surface of a cathodically pretreated BBDE (CPT‐BDDE) becomes enriched in HTs, whereas that of an anodically pretreated BDDE (APT‐BDEE) becomes enriched in OTs. Thus, when suitable, the electrochemical activity of a BDDE for a given analyte may be tuned by electrochemical pretreatments, yielding enhanced sensing properties. The main purpose of this review is the compilation and discussion of papers published after 2009 reporting on electroanalytical applications based on a CPT‐BDDE or an APT‐BDDE. Procedures to perform proper electrochemical pretreatments are also discussed.

Neste trabalho descreve-se a determinação do ácido acetilsalicílico (ASA) em formulações farmacêuticas empregando voltametria de onda quadrada (SWV) e um eletrodo de diamante dopado com boro (BDD). Neste método, ASA é determinado diretamente em solução de H 2 SO 4 0,01 mol L -1 , sem a necessidade da hidrólise alcalina. Foi obtido um único pico de oxidação no potencial de 1,97 V vs. Ag/AgCl (KCl 3,0 mol L -1 ) com características de uma reação irreversível. A curva analítica obtida é linear na faixa de concentração ASA de 2,50 × 10 -6 -1,05 × 10 -4 mol L -1 , com um limite de detecção de 2,0 µmol L -1 . O desvio padrão relativo foi menor que 1,4% para uma solução de ASA 45 µmol L -1 (n = 10). O método proposto foi aplicado com sucesso para a determinação de ASA em várias formulações farmacêuticas e os resultados obtidos foram concordantes com um método oficial da Farmacopéia Britânica, a um nível de confiança de 95%.In this paper the determination of acetylsalicylic acid (ASA) in pharmaceutical formulations using square-wave voltammetry (SWV) and a boron-doped diamond electrode (BDD) is described. By this proposed method, ASA is directly determined in a 0.01 mol L -1 H 2 SO 4 solution without the need of a previous time-consuming alkaline hydrolysis step. A single oxidation peak at a potential of 1.97 V vs. Ag/AgCl (3.0 mol L -1 KCl) with the characteristics of an irreversible reaction was obtained. The obtained analytical curve is linear in the ASA concentration range 2.50 × 10 -6 -1.05 × 10 -4 mol L -1 , with a detection limit of 2.0 µmol L -1 . The obtained relative standard deviation was smaller than 1.4% for a 45 µmol L -1 ASA solution (n = 10). The proposed method was applied with success in the determination of ASA in several pharmaceutical formulations; the obtained results were in close agreement, at a 95% confidence level, with those obtained using an official method of the British Pharmacopoeia.Keywords: acetylsalicylic acid determination, boron-doped diamond electrode, square-wave voltammetry, pharmaceutical formulations IntroductionAcetylsalicylic acid (ASA), shown in Figure 1, more popularly known as aspirin, is one of the oldest medicines that still plays an important role in modern therapeutics. It is widely employed in pharmaceutical formulations for the relief of headaches, fever, muscular pain, and inflammation due to arthritis or injury. It was first synthesized in 1897, by Felix Hoffmann, in the Farbenfabrik Freidrich Bayer laboratories, in Elberfeld, Germany. 1,2 The high consumption of this substance all over the world 3,4 indicates the importance of the development of new analytical methods to assess not only the quality but also the authenticity of the product.The rate of decomposition of ASA to salicylic acid (SA) and acetic acid (AA) is dependent on solution pH and temperature. In the pH range 11-12 ASA is quickly hydrolyzed, in the pH range 4-8 its hydrolysis rate is slow, and maximum stability is attained at pH 2-3. 5 Commonly, ASA is indirectly determined after its conversion to SA ...

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