Spectrofluorimetric assessment of doxycycline hydrochloride in pharmaceutical tablets and serum sample based on the enhancement of the luminescence intensity of the optical sensor Sm3+ ion.

A simple and sensitive spectrofluorimetric method for determination of trace amount of doxycycline hydrochloride (DC) in pharmaceutical tablets and serum samples was developed. In ammonia buffer solution of pH 8.9 the doxycycline hydrochloride can remarkably enhance the luminescence intensity of the Sm(3+) ion in Sm(3+)- DC complex at λ(ex)=400 nm. The produced luminescence intensity of Sm(3+)- DC complex in DMSO is in proportion to the concentration of DC and used as optical sensor for its determination. The dynamic range for the determination of DC is 1 × 10(-8)-5 × 10(-6) mol L(-1) and in case of quantum yield calculations is 7 × 10(-9)-5 × 10(-6) mol L(-1) with detection limit of 6.5 × 10(-10) mol L(-1). The enhancement mechanism of the luminescence intensity in the Sm(3+)- DC system has been also discussed. A comparison with other spectrofluorimetric methods for tetracycline derivatives in which Eu(3+) ion is used instead of Sm(3+) ion is also studied. © Springer Science+Business Media, LLC 2011