Hollow-fiber flow field-flow fractionation of whole blood serum

Hollow-fiber flow field-flow fractionation is here applied to untreated, whole human blood serum. Matrix-assisted, laser desorption/ionization time-of-flight-mass spectrometry (MALDI-TOF-MS) of serum fractions shows mass signals in the <30 000 Mr range where low-abundance, serum protein components are known to be present, though a membrane of nominal 30 000 Da cutoff was employed for the fractionation device. Using diluted sera spiked with low amounts (0.06–0.1%, w/w) of an artificial mixture constituted the human adrenocorticotropic hormone fragments 18–39 (Mr = 2465.7) and 7–38 (Mr = 3659.2), and of bovine insulin (Mr = 5734), horse cytochrome c (Mr = 12 384) and chicken lysozyme (Mr = 14 388), a hybrid fractionation/microfiltration mechanism shows to govern the separation of the low-Mr components.