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. Due to the
method's high 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 fluorometric estimation of TROX ethanolic 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. 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 Δ λ=60 nm. Therefore, DOB
was measured at 286 nm and 323 nm, while HQ could be quantitated at 301
nm. Beer's-Lambert law has complied over the ranges of 0.1- 1.0 µg/mL
and 0.02-0.4 μg/mL for DOB and HQ, respectively. Guidelines adopted by the
International Council of Harmonization (ICH) were used to validate the
target approaches. They were more convenient for routine quality control
laboratory instead of the time-consuming and sophisticated reported
techniques. Moreover, different aspects of evaluating the proposed
approaches' greenness were conducted to have a complete image of
their environmental impact.