Riboflavin’s time dependent degradation rate induced by ultra violet – A irradiation at 370 nm wavelength

Abstract

AbstractPurpose To evaluate the time dependent degradation rate of riboflavin standard solution used for corneal cross linking (CXL) treatment, after ultra violet – A irradiation at 370 nm wavelengthMethods Riboflavin solution (> 0.1%) was diluted in nanopurewater to a final concentration of 10 ppm. Two solutions were used, one served as control, while the second was irradiated using an optical system with a light source consisting of an array of UV diodes (370 nm). Four samples of riboflavin solution were retrieved prior to irradiance (time point: 0), at 1, 5, 15, 30 and 60 minutes after irradiation (Group A); while, at the same time points samples of riboflavin were retrieved from the control solution in order to assess environmental time ‐ induced degradation of riboflavin (Group B). All samples were immediately analyzed using liquid chromatograph mass spectrometry to detect riboflavin and its two sub products (lumiflavin and lumichrome)Results The mean percentage of riboflavin degradation was 2.38, 11.08, 15.30, 20.75 and 34.78 at 1, 5, 15, 30 and 60 minutes after UV‐A irradiation for Group A (p<0.05), while for group B (no UV‐A exposure) there was no change in riboflavin concentrationConclusion The time dependent degradation of standard riboflavin solution is significant, reaching after 30 minutes of UV‐A exposure 20%. It seems that only a small fraction of the overall riboflavin molecules break down since, more than 65% remain intact even after one hour of UV‐A irradiation