Determination of tetracyclines with a modified β-cyclodextrin based fluorosensor

An ethyl substituted β-cyclodextrin based fluorosensor was prepared for the determination of tetracyclines in clinial samples. The analytical performance characteristics of the proposed sensor for analysis of very low levels of tetracycline (TC), oxytetracycline and chlorotetracycline were as follows: the linear ranges were 9–800, 20–1000 and 25–1000 nM, respectively. The detection limits were 4.0, 7.5 and 9.0 nM. The relative standard deviation for 11 determinations of 1 μM of each antibiotic was 1.1%. The proposed optosensor has a higher selectivity. Species existing in biological samples hardly interfered, and the main interferences were caused by some metal ions which can complex with TC and enhance its fluorescence. They could be masked by adding excess of EDTA. The recommended method has been successfully tested for determining tetracycline in clinical samples (urine and pharmaceutical preparations).