Riboflavin (vitamin B2) is water-soluble and photosensitive. It is present in milk, green leafy vegetables and egg.
Riboflavin fluoresces at wavelength 440 to 500nm. The intensity of fluorescence is proportional to the concentration of riboflavin in dilute solutions. The riboflavin is measured in terms of the difference in fluorescence before and after chemical reduction.
» Sodium Acetate 2.5M
» Potassium Permanganate 4% (Prepare fresh every time)
» Hydrogen Peroxide 3%
» Riboflavin Standard
Dry standard riboflavin over P2O5 in a desiccator for 24h. Dissolve 50mg in 1500mL water and 2.4mL glacial acetic acid in a two liter flask. Warm, cool and make up to volume. Store under toluene in amber bottles in a refrigerator (25mg/mL).
Dilute 20mL of the above riboflavin standard solution to 50mL with water. For working solution, dilute 10mL of the second riboflavin standard solution with water to 100mL. Prepare this dilution fresh. Protect from light. (1mL = 1mg riboflavin)
» Sodium Hydrosulphite (solid)
A = reading of the sample plus riboflavin standard
B = reading of sample plus water
C = reading after adding sodium hydrosulphite
R = standard riboflavin added = mg/V1 of sample solution
V = original volume of sample solution = mL
V1 = volume of sample solution taken for measurement (10mL)
S = sample weight (g)
In this dilution R = 1; V = 100 and V1 = 10.
1. American Association of Cereal Chemists (1976) (compiled — approved methods committee) AACC Inc St Paul Minn USA 2.
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