Disclosed are methods for direct characterization of microdomains and/or three-dimensional microstructure arrays bearing high densities of reactive sites using Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometery (MALDI-MS) and other analytical techniques. The high site density of the arrays can provide sufficient sample of each array element and/or materials bound to each element to obtain directly using common analytical techniques such as MALDI-MS. Spatially directed synthesis of heteropolymers is done through the use of pliotolabile, electrically labile, and chemically labile protecting group(s).