Determination of vitamin B2 (Riboflavin) using spectrophotometric and spectrofluorometric methods.

This work involved the use of UV-VIS spectrometry and fluorescence spectrometry in the determination of riboflavin in vitamin samples directly from the riboflavin present in sample and indirectly by conversion of riboflavin to its photoderivatives. Standard solutions of riboflavin were prepared at different pH range
from (2-10) to measure the maximum absorbance at beast pH. Riboflavin show maximum absorbance at 445 nm at pH 4. This wavelength and pH were used to determine riboflavin concentration in vitamin samples, the recovery of this method was 99.14% with relative error of 0.86%. Scanning the emission spectrum of riboflavin (at 445nm as excitation wavelength) show a maximum emission at 520nm. This emission wavelength was used to determine the riboflavin concentration in vitamin samples. The recovery of this method was 99.44% with a relative error of 0.55%. Indirect determination of riboflavin was based on the conversion of riboflavin to its photoderivative after irradiation the vitamin samples with UV light. The two main derivatives were lumiflavine in basic media and lumichrome in acidic media. Different standard solutions of riboflavin prepared at different pH were irradiated to produce the highest percentages of Photodegradation products. The percentage of degradation of each derivative was determined using beer's law. The lumiflavine produced show a maximum absorbance at 352 nm at pH9. This wavelength and pH were used to determine the concentration of riboflavin in vitamin sample. The recovery of this method was 94.15% with a relative error 5.85%. Spectrofluorometric scanning of lumiflavine showed a maximum emission at 422nm. This wavelength was used to indirect determination of riboflavin in vitamin samples. The recovery of this method was 95.00% with a relative error of 5.00%. The spectrum produced from the acidic photoderivative product (lumichrome), showed a maximum absorbance at 350 nm at pH2. The determination of riboflavin using lumichrome gave a recovery of 91.05% with relative error of 8.85%. Using Spectrofluorometric method, scanning of lumichrome showed a maximum emission at 468nm. This method gave a recovery of 91.95% with relative error of 8.05%. Spectrofluorometric method has shown better recovery and less error than the corresponding spectrophotometric method