QUALITATIVE-ANALYSIS OF SOLID-PHASE SYNTHESIS REACTION-PRODUCTS BY X-RAY SPECTROMETRY

A novel method for the synthesis of polypeptides using polystyrene/div inylbenzene copolymers as solid supports has drawn the attention of me dicinal, pharmaceutical, and agricultural chemists because of its util ity in combinatorial chemistry and parallel synthesis. In this method, arrays of solid-phase organic synthesis experiments are conducted sim ultaneously thereby enabling the preparation of large numbers of novel compounds over a short time period. The analysis of organic compounds attached to polymer supports presents unique challenges to chemists. This study presents some results of the application of energy-dispersi ve X-ray spectrometry (EDS) in the environmental scanning electron mic roscope (ESEM) to this problem. EDS in the ESEM has the advantages of minimal sample size, speed, and simplicity because the analyses are pe rformed without special specimen preparation. The progress of a two-st ep synthetic transformation was followed using EDS-ESEM by the presenc e of a sulfur peak in the first synthetic step and by a bromine peak i n the second step. The synthetic products were also evaluated by infra red spectroscopy and by elemental analysis (ion chromatography). The a greement of the qualitative analysis among all three techniques was go od. Analysis by EDS-ESEM not only complements current analytical techn iques in solid phase synthesis; it also provides insight into the deta ils of the synthetic transformation.