Original Rapid UV-Vis Spectrophotometric Quantification of Ferrous Bisglycinate in Food Supplements

Ferrous bisglycinate is a salt of the glycine amino acid, and in recent years it has replaced many traditional ferrous salts used in food supplement production. The main advantage of ferrous bisglycinate is its better absorption and that at the same time it is gentle to the digestive system. Development and validation of reliable analytical methods for food supplement control is very important for improving the quality of the products on the market. The current work presents a validated UV-Vis analytical procedure for determination of the content of ferrous bisglycinate in food supplements. The described method is quick colourimetric determination and does not require complicated analytical instruments. The method is reproducible, accurate, precise and linear in a wide range from 0.15 µg/ml to 9.10 µg/ml with linearity coefficient 0.9999. The main problem is to convert existing traces of Fe3+ ions in the substance to Fe2+ ions and to analyse all available ferrous species. For this reason, initially we need to destroy the complex of glycine with Fe2+/3+ ions, to reduce Fe3+ to Fe2+, and then to form a new complex of Fe2+ stable at the conditions of the analytical procedure.