RESUMO
For the first time ever, useful fluorescent (FL) carbonaceous materials (CMTS) were isolated from incense ash using facile procedure on two steps; dispersion of the CMTS in water followed by filtration. The CMTS were characterized using the following techniques; dynamic light scattering (DLS), transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) spectroscopy. The CMTS exhibit excitation wavelength dependent fluorescence emission, so it can be used as a FL probe. The FL probe was employed for sensing and quantitative determination of two members of oxicam family (tenoxicam (TEN) and meloxicam (MEL)) that belongs to non-steroidal anti-inflammatory drugs (NSAIDs). The method is based on the quenching of the FL intensity of the isolated CMTS by inner filter effect mechanism (IFE). The FL intensity decreases in linear relationship with increasing the concentrations of the two cited drugs within the range of 4.0 - 30.0 µg/mL with mean percentage recoveries of 100.04 ± 0.95 and 100.07 ± 1.06 with detection limits of 1.31 µg/mL and 1.06 µg/mL for TEN and MEL, respectively. Finally, the developed sensing system was validated as per ICH guidelines and it was proved to be accurate and precise and applied successfully for quantitative determination of the two cited drugs in their capsule dosage forms with excellent percentage recoveries reaching to 97.66 ± 0.39and 98.19 ± 1.12 for TEN and MEL, respectively.
