Stability-indicating spectrofluorimetric method with enhanced sensitivity for determination of vancomycin hydrochloride in pharmaceuticals and spiked human plasma: Application to degradation kinetics.

Based on investigating the relative fluorescence intensity of vancomycin hydrochloride (VCM) in methanol, a simple, highly sensitive, time-saving and specific spectrofluorimetric method was developed and validated. VCM fluorescence was measured at 335 nm when excited at 268 nm. Excellent linearity is obeyed in the concentration range 1-100 ng/mL with a detection limit of 5.94 pg/mL, a quantitation limit of 18.03 pg/mL and a very good correlation coefficient (r = 0.9999). Our method was applied to analyze VCM in pharmaceuticals as well as spiked human plasma. Moreover, VCM stability was studied when exposed to various degradation conditions such as oxidative, alkaline as well as acidic stress. Acidic and alkaline degradation kinetics of VCM was studied for the first time. The degradation follows pseudo-first-order kinetics. The apparent rate constants and half-life times were calculated. The Arrhenius equation was assessed and the activation energies of the degradation were also calculated. The developed method can be easily applied in quality control laboratories due to its sensitivity, specificity, simplicity and low cost.