| Abstract
| - A near-infrared (NIR) multispectral imaging spectrometerwas used to monitor solid-phase peptide synthesis. Thisimaging spectrometer has fast scanning ability and highsensitivity because it is based on an acousto-optic tunablefilter and a NIR InGaAs focal plane array camera. ThisNIR imaging instrument possesses all the advantages ofconventional NIR spectrometers; namely, it can be usedfor noninvasive monitoring of the reactions and identification of the products during the solid-phase peptidesynthesis of glycine, alanine, and valine mediated byaminomethylstyrene resin beads. The reaction was determined by monitoring either the decrease of the band at1529 nm, which is due to the amine group on the beads,or the increase of the amide band generated at 1483 nm.The amine band at 1529 nm was also used to determinethe presence of the Fmoc protecting groups and theefficiency of its removal. More importantly, this NIRimaging spectrometer has additional features that conventional NIR spectrometers cannot offer; namely, itsability to measure spectra at different positions within asample. This feature was utilized for the first demonstration in which reactions of three different solid-phasepeptide syntheses (in a three-compartment cell) weresimultaneously monitored. As expected, the kineticsobtained for three reactions are similar to those obtainedwhen the each of the reactions was individually determined. In this study, data recorded by 16 × 16 pixelswere used to calculate a spectrum for each sample.However, a relatively good spectrum can be obtained byusing data recorded by a single pixel. Since the NIRcamera used in this camera is equipped with 240 × 320pixels, this NIR mutispectral imaging technique is notlimited to the three-compartment cell used in this studybut rather can be used as the detection method for thesolid-phase peptide synthesis in combinatorial chemistry.
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