Ethyl substituted β-cyclodextrin enhanced fluorimetric method for the determination of trace amounts of oxytetracycline in urine, serum, feed of chook and milk

A simple sensitive spectrofluorimetric method was developed for the determination of oxytetracycline (OTC). Ethyl substituted β-cyclodextrin (DE-β-CD) can remarkably enhance the fluorescence intensity of the OTC-Eu3+ complex at λ=612nm and the enhanced fluorescence intensity of Eu3+ ion is in proportion to the concentration of OTC. Optimum conditions for the determination of OTC were also investigated. The linear range of this method for the determination of OTC is 8.28×10−8-1.73×10−5 mol/L and the limit of detection is 6.76×10−9 mol/L, respectively. The developed method is practical and relatively free interference from coexisting substances and can be successfully applied to determination of OTC in samples of urine, serum, feed of chook and milk. The enhancement of the fluorescence at λem=612 nm of Eu3+ ion is because of the inclusion complex OTC-Eu3+-DE-β-CD.