Design and Optimization of Oxytetracycline Determination using Vigna unguiculata subsp. sesquipedalis Extract as Green Reagent by Response Surface Methodology

The research aims to design and optimize parameters which affect to the efficiency for determination of oxytetracycline. The oxytetracycline assay is based on the complex formed between oxytetracycline and iron(III) contained in Vigna unguiculata subsp. sesquipedalis, yielding a yellow colored complex in an acetate buffer medium (pH 6.0) which gave the maximum absorption at 430 nm using UV-Visible spectrophotometry. Parameters related to the efficiency for oxytetracycline determination such as pH, green reagent volume and time of reaction were design and analysis using Response Surface Methodology (RSM) by Box-Behnken design (BBD). Under the optimum conditions, a linear calibration graph was obtained in the concentration range 1.00-30.00 mg L
^-1
. Detection limit (LOD, defined as 3σ) and limit of quantification (LOQ, defined as 10σ) were 0.43 and 1.41 mg L
^-1
, respectively. The relative standard deviation (R.S.D.) of 3.25% for determining 10.00 mg L
^-1
of oxytetracycline (n=11) are obtained. The proposed method has been applied to the oxytetracycline assay in honey samples. Results obtained were in good recoveries in the range of 86.00-116.10%.