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Rapid Screening of Oxytetracycline Residue in Fish Muscle by Dispersive Liquid-Liquid Microextraction and Europium-Sensitized Luminescence

Guoxin Lai, Guoying Chen, Tuanwei Chen, Qiongqiong Li
Food analytical methods 2015 pp. -
EDTA (chelating agent), Food and Drug Administration, acetonitrile, analytical methods, catfish, chemical residues, europium, hydrochloric acid, liquid-phase microextraction, luminescence, muscles, oxytetracycline, rapid methods, screening, solid phase extraction, solvents, wavelengths
Oxytetracycline (OTC) residue in catfish muscle was screened by dispersive liquid-liquid microextraction (DLLME) and europium-sensitized luminescence (ESL). After extraction in EDTA, HCl, and acetonitrile, cleanup was carried out by DLLME, and ESL was measured at microgram = 385 nm and wavelength = 620 nm using a portable fluorometer. The screening threshold was set at T=x-3sigma2, where x2 and s2 were mean and standard deviation of twenty catfish muscle samples spiked at 2 ug/g, the tolerance set by Food and Drug Administration. Among 49 samples randomly spiked with OTC at 0-4 ug/g, 43 were screened correctly without false negative, but 6 negatives were classified as presumptive positives. This rapid, reliable, and low-cost method reduced usage of chlorinated solvents, eliminated solid phase extraction, and significantly improved sample throughput.