Rapid Fluorimetric Quantitation of Ibandronate by Coupling Quantum Dots and Multicommutated Flow Injection Analysis

Ibandronate is a potent nitrogen-containing bisphosphonate with a tertiary amine group, which does not easily form chromophore derivatives that can be detected by UV light of fluorescence emission. Here, a simple and straightforward automated multicommutated flow system, making use of water-soluble mercaptopropionic acid-capped CdTe quantum dots, was implemented for the fluorescence quantitation of ibandronate in pharmaceutical formulations. The developed approach was based on the analyte ability to establish surface interactions that resulted in quenched nanocrystals fluorescence intensity, being this effect proportional to the target compound's concentration. Size and concentration of quantum dots and pH of the media were some of the most relevant and influencing parameters studied. The proposed methodology allowed the determination of ibandronate in the range of 20-200 µg mL-1, with good repeatability (RSD<3%) and a sampling frequency of about 70 samples per hour. The results obtained in the analysis of pharmaceuticals showed excellent agreement with those provided by the manufacturer.