FIGURE 4.

LC-MS of acetonitrile (ACN) supernatant compared with 30K nominal molecular weight filtrate. Total ion chromatograms of ACN-precipitated serum (A) and reconstituted filtrate (B) are shown. C and D show the averaged mass spectra overlay from 18 to 27 min cLC elution for the serum and the filtrate respectively. ACN-precipitated serum is shown in blue, the filtrate is shown in red. Comparison of C and D shows that the ACN precipitation method was superior to the centrifugal ultrafiltration technique in both number of low-molecular-weight species and intensity of peaks.