Determination of total riboflavin in cooked sausages

A simple and rapid method for determining riboflavin content in cooked sausages by ion-pair reversed-phase liquid chromatography has been set up. Samples were subjected to acid and enzymatic hydrolysis. Sample extracts were directly chromatographed, avoiding purification and concentration treatment. Final determination was performed by high-performance liquid chromatography with fluorescence detector (excitation, 227 nm; emission, 520 nm), on a 25 cm x 4 mm i.d. Spherisorb ODS-2 cartridge using a mixture of 5 mM heptanesulfonic acid adjusted to pH 2.7 with phosphoric acid and acetonitrile (75:25, v/v) as mobile phase. Precision of the method was 1.3% (within a day) and 2.6% (between days). The detection limit was 0.015 mg/100 g. The recovery was >95%.