Reduction of composite NMR spectra by using an analog computer

Abstract

AbstractAn analog computer program has been devised to resolve complex composite curves such as might be encountered in various forms of spectroscopy or chromatography. Seven Gaussian or Lorentzian curves, or any combination of seven curves, can be used and displayed simultaneously to resolve the composite curves. Various degrees of skew and truncation, as well as slanted and curved baselines, can be introduced. The peak amplitude, width and position can be determined from potentiometer settings. The integrated relative area of each of the peaks is read out on a digital voltmeter with a reproducibility of about ±0.1%. The utility of the technique is demonstrated by resolving highly overlapped peaks in NMR spectra of butadiene–styrene copolymers. It is necessary to use as many as eight curves to resolve the styrene aromatic proton resonance. This analysis yields styrene‐centered distributions and styrene sequence distributions from the NMR spectra of butadiene–styrene copolymers. In addition, it is shown that a distinction can be made between short styrene sequences, which contain two and three styrene units, and long styrene sequences, which include all sequences longer than three units.