5-methyltetrahydrofolic acid and folic acid measured in plasma with liquid chromatography tandem mass spectrometry: applications to folate absorption and metabolism

Kok R. M., Smith D. E. C., Dainty J. R., van den Akker J. T., Finglas P. M., Smulders Y. M., Jacobs C., de Meer K.. (2004)

Analytical Biochemistry, 326, 129-138