Disposable polymeric high-density nanovial arrays for matrix assisted laser desorption/ionization-time of flight-mass spectrometry: II. Biological applications

A novel disposable high-density matrix assisted laser desorption/ionization (MALDI) target plate made either from polymethylmethacrylate (PMMA) or pol ycarbonate (PC) is presented where thousands (1200-1600) of samples can be deposited and subsequently, analyzed by MALDI-time of flight (TOF) mass spe ctrometry. Good reproducibility, was obtained across the plate regardless o f position on the target plate with a relative standard deviation (RSD) on the peak intensity of typically 30% calculated from data generated by analy sis of a 10 nM peptide mixture of angiotensin. I, II, III and bradykinin. T he nanovial array format combined with microdispensing technology makes It possible to carry out in-vial, chemistry on deposited samples. This is demo nstrated by the analysis of peptides from beta -casein and subsequent in-vi al dephosphorylation of its phosphopeptides at 10 fmol levels by microdispe nsing of alkaline phosphatase, into the nanovial. The mass spectra obtained from these polymeric targets provides can also be used in high sensitivity applications as shown by peptide mass fingerprinting of human fibroblast p roteins separated by two-dimensional gel, electrophoresis.