Investigation of the fluorescence of benoxinate for facile etermination in pure form, eye drops and aqueous humor

A new approach to determine the local anesthetic benoxinate spectrofluorimetrically was developed. It was found that benoxinate exhibits strong native fluorescence in ethanol at 371 nm after excitation at 297 nm. There was a linear response between the fluorescence intensity and the concentration of the studied drug over the range of 10.0–100.0 ng/ mL. The suggested spectrofluorimetric method was optimized and validated following the pharmacopoeial guidelines. The obtained results were fully discussed and statistically analyzed in relevance to a previous published spectroscopic method. The limit of quantification (LOQ) of the present method was 1.79 ng/mL. Inter-day and intra-day precision relative standard deviations were lower than 1.5%. Finally, the proposed methodology has been adopted for determination of benoxinate in aqueous humor with a mean percentage recovery 99.87 ± 1.66 as well as in the pharmaceutical eye drops with a mean percentage recovery 100.37 ± 1.32. The method is cost-effective and green as it depends in water and ethanol mainly.