Extraction and Determination of Oxytetracycline Hydrochloride and Oxolinic Acid in Fish Feed by Derivative Spectrophotom
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Extraction and Determination of Oxytetracycline Hydrochloride and Oxolinic Acid in Fish Feed by Derivative Spectrophotometry of First Order M. Inés Toral & Sandra L. Orellana & César A. Soto & Pablo Richter
Received: 4 October 2010 / Accepted: 5 January 2011 / Published online: 18 January 2011 # Springer Science+Business Media, LLC 2011
Abstract In this work is proposed the extraction and determination of oxytetracycline (OTC) and oxolinic acid (OA) in fish feed by first-derivative spectrophotometry. The extractions are carried out by parallel modality, where OTC is extracted in the presence of OA in a sample, and in another is extracted OA in the presence of OTC, and the sequential modality, where OTC is extracted first and then followed by OA in a single feed sample. A phosphate buffer, pH 7.0, was selected for OTC extraction and acetonitrile for OA extraction. These solvents were used in both extraction modalities. The extraction percentages obtained by parallel mode are better than those obtained by sequential extraction. In both cases, the limits of extraction were 25 mg kg−1 for OTC and 10 mg kg−1 for OA. However, it is proposed to work with the parallel extraction for its efficiency, accuracy, precision, and less time requirement. Keywords Oxytetracycline . Oxolinic acid . Extractions . Derivative spectrophotometry . Feed
M. I. Toral (*) : S. L. Orellana Department of Chemistry, Faculty of Sciences, University of Chile, 653, Santiago, Chile e-mail: [email protected] C. A. Soto Department of Inorganic and Analytical Chemistry, Faculty of Chemical Sciences, University of Concepción, 160-C, Concepción, Chile P. Richter Department of Inorganic and Analytical Chemistry, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, 233, Santiago, Chile
Introduction Oxytetracycline (OTC), an antibacterial broad-spectrum antibiotic belonging to the family of tetracyclines (TCAs), is widely used in aquaculture. Its mechanism of action is to inhibit the synthesis of bacterial proteins being fixed to 30S ribosome subunit (Chopra and Roberts 2001). Its structure presents a hydronaphthacene skeleton containing four fused rings, showing acid–base properties due to the presence of amino and hydroxyl groups. In general, chelating properties of TCAs are due to the presence of ketone and enol groups, and their antibacterial activity and pharmacokinetic properties are influenced by the chelation of metal ions (Arias et al. 2005). Oxolinic acid (OA) is another synthetic antibiotic used regularly in the salmon industry. It belongs to the family of quinolones, which have in common the presence of a 4-quinolone-3-carboxylate ring. The first action site described for these antibiotics was the bacterial enzyme DNA gyrase, a bacterial topoisomerase II. Quinolones inhibit some of the catalytic activities of DNA gyrase in bacteria (Hooper 1999). In this context, quinolones exert their toxicity on the bacterial cell, stabilizing the double strand of DNA that has been broken by the DNA gyrase so that the subsequent ligation ca
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