Simultaneous estimation of troxerutin and calcium dobesilate in presence of the carcinogenic hydroquinone using green spectrofluorimetric method.

In the present study, we conducted two facile and highly sensitive spectrofluorimetric approaches in order to quantify the vasoprotective agents; troxerutin (TROX) and calcium dobesilate (DOB) in the presence of hydroquinone (HQ) (as a highly toxic impurity and potential degradation product of DOB) in commercial formulations and human plasma. The first approach relies simply on using ethanol as an eco-friendly solvent for the estimation of DOB at 345 nm after being excited at 305 nm. The linearity was carefully investigated between DOB concentration and the relative fluorescence intensity in the range of 0.05-0.8 µg ml-1. Due to the high method simplicity and sensitivity, applying the first approach to quality control analysis and spiked human plasma samples with mean % recoveries 100.74 ± 3.71 adds another merit. The second approach involved rapid conventional fluorimetric estimation of ethanolic TROX solution in TROX/DOB combined dosage forms at 455/350 nm (emission/excitation) with a linear calibration chart covering the range of 0.1-1.2 µg ml-1. Moreover, the second approach involved a comprehensive study in a trial to solve the problem of superposition of DOB and HQ graph adopting the first derivative synchronous fluorimetric mechanism in ethanol at Δλ = 60 nm. Therefore, DOB was measured at 286 and 323 nm, while HQ could be quantitated at 301 nm. The Beer-Lambert Law has complied over the ranges of 0.1-1.0 and 0.02-0.4 µg ml-1 for DOB and HQ, respectively. Guidelines adopted by the International Council of Harmonization (ICH) were used to validate the target approaches. The developed methods are more convenient for routine quality control laboratory instead of the time-consuming and sophisticated reported techniques. Moreover, different aspects of evaluating the greenness of the proposed approaches were conducted to have a complete image of their environmental impact.