Cadmium Sulfide Quantum Dots as a Fluorescent Probe for Quantitative Determination of Cefixime

Water-soluble fluorescent CdS quantum dots (QDs) capped with thioglycolic acid (TGA) were prepared. The resulting QDs have characteristic emission maximum at 514 nm after excitation at 370 nm. Fluorescent QDs were used for the quantification of cefixime based on its quenching effect on the fluorescence intensity of the QDs. Maximum fluorescence quenching was observed when 0.3 mM of QDs were mixed with cefixime and allowed to stand for 5 min. At optimum experimental conditions, the Stern-Volmer calibration plot of F-o/F against concentration of cefixime was linear in the range of 2-40 mu g/mL. The limit of detection (3.3SD/b) and limit of quantification (10SD/b) were found to be 1.3 and 3.9 mu g/mL respectively with RSD a parts per thousand currency sign 1.56%. The proposed method was successfully applied to commercial formulations with % recovery in the range of 97.17 +/- 1.16-100.15 +/- 0.61.The results were compared with reference methods and evaluated statistically using student t-test and variance ratio F-test.