Determination of Oxytetracycline from Salmon Muscle and Skin by Derivative Spectrophotometry

• Published in: Journal of AOAC International 2015-05, Vol.98 (3), p.559-565
• Main Authors: Toral, M Inés, Sabay, Tamara, Orellana, Sandra L, Richter, Pablo
• Format: Article
• Language: English
• Subjects: Animals; Anti-Bacterial Agents - analysis; Chemical properties; Chromatography, High Pressure Liquid; Contamination; Drug Residues - analysis; Food Analysis; Identification and classification; Indicators and Reagents; Methods; Muscles - chemistry; Oxytetracycline - analysis; Reproducibility of Results; Salmon; Salmon - metabolism; Skin - chemistry; Spectrophotometry; Spectrophotometry, Ultraviolet; Tetracycline; Tetracyclines
• ISSN: 1060-3271; 1944-7922
• DOI: 10.5740/jaoacint.14-027

A method was developed for the identification and quantification of oxytetracycline residues present in salmon muscle and skin using UV-Vis derivative spectrophotometry. With this method, it was possible to reduce the number of steps in the procedure typically required for instrumental analysis of a sample. The spectral variables, order of the derivative, scale factor, smoothing factor, and analytical wavelength were optimized using standard solutions of oxytetracycline dissolved in 900 mg/L oxalic acid in methanol. The matrix effect was significant; therefore, quantification for oxytetracycline residues was carried out using drug-free salmon muscle and skin samples fortified with oxytetracycline. The LOD and LOQ were found to be 271 and 903 μg/kg, respectively. The precision and accuracy of the method were validated using drug-free salmon muscle and skin tissues fortified at three different concentrations (8, 16, and 32 mg/kg) on 3 different days. The recoveries at all fortified concentrations were between 90 and 105%, and RSDs in all cases were less than 6.5%. This method can be used to screen out compliant samples and thereby reduce the number of suspect positive samples that will require further confirmatory analysis.