Amperometric and voltammetric determination of oxytetracycline in trout salmonid muscleusing multi-wall carbon nanotube, ionic liquid and gold nanoparticle film electrodes

The use of a multi-wall carbon nanotube, ionic liquid and gold nanoparticle film glassy carbon electrode to determine oxytetracycline (OTC), one of the mostly used antibiotics in salmon industry, by amperometry and adsorptive stripping voltammetry (AdSV) is reported. Electrodes were coated with [BMIM]3F₅EPF₃, [EMIM]F₃MSO₃, [BMIM]PF₆and [BMIM]BF₄, achieving the highest sensitivity with [BMIM]BF4. Using AdSV, variables like pH, scan rate (ν), accumulation potential, and time (Eacc, tacc) were optimized. The best experimental conditions were: pH = 7.0; ν = 0.60 V s^-1; Eacc = 0.40 V, and tacc = 70 s. The relative standard deviation obtained was 1.5% (n=5) for a solution containing 5.0x10^-6 mol L^-1 of OTC. Using AdSV and amperometrictechniques, the linear calibration curves ranged up to 8.0x10^-6 mol L^-1 and the detection limits (3σ) were 1.5x10^-7 and 2.0x10^-8 mol L^-1, respectively. The methods were validated using fish tissue spiked with OTC. Because the sensitivity of the amperometric technique is higher than AdSV, the analysis of fish tissue samples was made using the former technique, getting aLoD of 5.3x10^-10mol L^-1.