Investigation of Colorant FD&C Yellow No. 5 Stability in Pharmaceutical Syrup Containing Ascorbic Acid and the Optimal Storage Condition

Stability of colorant FD&C Yellow No. 5 and ascorbic acid (AA) in pharmaceutical KndCold syrup under different storage conditions (Standard conditions, temperature variation, sunlight presence, and sodium hydroxide addition) have been investigated. Under the standard conditions, 18.6% of ascorbic acid in solution converted, while pulling the samples out to indirect sunlight, color intensity was increased by 53%., and AA loss was recorded as 19.1%. Storage temperature was had a harsh effect on AA degradation and color intensity, specifically the loss of AA and color intensity boost was 2.1%, 16.8%, 24.7% and 2.8%, 40%, 53.1%, at 0, 20, and 40°C, respectively. Subsequently, the role of pH was investigated by adding a base such as NaOH. The addition of the base produces the different pH syrups: 4.5, 5.8, and 7.4. A sample of pH 7.4 fulfills the lowest AA degradation rate, nearly 5.7%, similarly for color intensity change. In conclusion, ascorbic acid degradation in KndCold syrup has a direct influence on the concentration of the yellow color. The optimal conditions for processing the yellow colored pharmaceutical syrups, which contains ascorbic acid, could be a temperature below 10°C, the completely absence of sunlight, and basic solution pH.