The use of non-porous membranes as sample supports for MALDI-TOFMS analysis of peptides and proteins as well as for the analysis of whole blood is herein described. Non-porous membranes have a uniform surface, allowing for greater sensitivity and accuracy. Specifically, the non-porosity favours crystal growth on the surface of the membrane only, thereby providing enhanced spectral quality over membranes with porous structures. Studies were performed using polyurethane (PU) membranes as an example of non-porous MALDI sample supports and showed that PU membranes yielded higher quality spectra compared with porous membrane sample supports such as polyether and poly(vinyl difluoride) and the spectra obtained from PU membranes are of comparable quality as those obtained with metallic targets. However, the sample preparation for use with PU membranes is much less arduous compared with the preparation necessary for metallic targets. On membrane proteolytic digestions of proteins were performed using trypsin. After the completion of the digests, buffer components were washed of leaving peptides bound to the membrane. Addition of matrix followed by MALDI analysis resulted in good quality mass spectra which enabled peptide mapping.