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).
 The research leading to this invention was funded in part by the Department of Energy by grant no. DE-FCS36-05GO15016 and the National Science Foundation by grant no. CHE-0131222. The U.S. Government may have certain rights in this invention.