Determination of Sudan II dye in ethanol fuel by chromatographic and electroanalytical methods

Author(s)

Goncalves Trindade, Magno Aparecido ; Romanini, Daiane Cristina ; Boldrin Zanoni, Maria Valnice

• Document type: Journal article
• Source: BRAZILIAN JOURNAL OF ANALYTICAL CHEMISTRY; v. 2, n. 8, p. 8-pg., 2012-04-01.

Abstract

Chromatographic and electroanalytical methods were developed to detect and quantify Sudan II (SD-II) dye in fuel ethanol samples. Sudan II is reduced at +0.50 V vs. Ag/AgCl on a glassy carbon electrode using Britton-Robinson buffer (pH 4.0) and N, N-dimethylformamide (70: 30, v/v) + sodium dioctyl sulfosuccinate surfactant as supporting electrolyte, due to the azo group. This is the basis for its determination by square-wave voltammetry (SWV). Using the optimized conditions, it is possible to get a linear calibration curve from 3.00x10(-6) to 1.80x10(-5) mol L-1 (r = 0.998) with limits of detection (LOD) and quantification (LOQ) of 2.05x10(-6) and 6.76x10(-6) mol L-1, respectively. In addition, the hydroxyl substituent in the SD-II dye is also oxidized at + 0.85 V vs. Ag/AgCl, which was conveniently used for its determination by high-performance liquid chromatography coupled to electrochemical detection (HPLC-ED). Under the optimized condition, the SD-II dye was eluted and separated using a reversed-phase column (cyanopropyl, CN) using isocratic elution with the mobile phase containing acetonitrile and aqueous lithium chloride (5.00x10(-4) mol L-1) at 70: 30 (v/v) and a flow rate of 1.2 mL min(-1). Linear calibration curves were obtained from 3.00x10(-7) to 2.00x10(-6) mol L-1 (r = 0.999) with LOD and LOQ of 3.10x10(-8) and 1.05x10(-7) mol L-1, respectively. Both methods were simple, fast and suitable to detect and quantify the dye in fuel ethanol samples at recovery values between 83.0 to 102% (SWV) and 88.0 to 112% (HPLC-ED) with satisfactory precision and accuracy. (AU)