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 M(r) 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 (M(r)=2465.7) and 7-38 (M(r)=3659.2), and of bovine insulin (M(r)=5734), horse cytochrome c (M(r)=12384) and chicken lysozyme (M(r)=14388), a hybrid fractionation/microfiltration mechanism shows to govern the separation of the low-M(r) components.