CHAPTER 18: Assays of Riboflavin in Food using Solid-phase Extraction

The determination of riboflavin in food is relevant due to its role as nutrient, as a marker of processing and storage conditions or as a natural colorant additive. Solid-phase extraction is a suitable treatment for the separation of riboflavin from interfering compounds present in complex food matrices. Several methods have been reported for solid-phase extraction of riboflavin in different types of food, followed by chromatographic separation and quantification by spectrophotometric or fluorimetric detection. Besides batch extraction protocols, solid-phase operation was automated, with offline or online integration to high-performance liquid chromatographic (HPLC) determination. Several aspects of the proposed methods are discussed, namely the types of sorbent applied, concomitant sample treatments and the riboflavin form quantified (total, free or other forms).