Isotope dilution-liquid chromatography/mass spectrometric method for the determination of riboflavin content in multivitamin tablets and infant formula

Abstract Isotope dilution liquid chromatography/mass spectrometry (ID-LC/MS) was developed to measure riboflavin contents in infant formula and multivitamin tablets. 13 C 4 , 15 N 2 -riboflavin was used as an internal standard. For infant formula, acid hydrolysis was conducted after spiking internal standard to release bound riboflavin. Free riboflavin in the multivitamin tablets was extracted with distilled water for 3 h at 4 °C. The mass spectrometer was operated in selected ion monitoring mode to observe the collisionally induced dissociation channels of m / z 377 → 243 for riboflavin and m / z 383 → 249 for 13 C 4 , 15 N 2 -riboflavin. The developed method was validated based on tests of repeatability and reproducibility, evaluation of measurement uncertainty, and analysis of available certified reference materials. For infant formula and multivitamin samples, the repeatability was 0.1–0.4% and 0.3–1.2%, and the reproducibility was 1.4 and 1.0%, respectively. The realtive expanded uncertainty of analyzing homogenized sample was ranging 1–4%. Therefore, the developed method showed that it has as a high-order metrological quality. The developed ID-LC/MS method was also tested for the accurate analysis of riboflavin in commercial food products including infant formula, breakfast cereals, milk, and multivitamin tablets.