The use of a high resolution NMR spectrometer controlled by a dedicated computer for quantitative analytical chemistry.

Abstract

AbstractOperational complexity of high resolution NMR spectrometers has severely limited their use in quantitative analysis in spite of the many inherent advantages of the NMR technique. In order to demonstrate the feasibility of routine analyses in a rapid and accurate fashion with no special demands on the skill of the operator, the authors have programmed a small general purpose computer to control an NMR spectrometer, maintain adjustment of critical operating parameters, acquire data, numerically integrate appropriate spectral regions, calculate results and errors, and print out a teletype record of results. The unsaturation in natural edible oils, expressed as the iodine number and a polyunsaturation factor, has been chosen to illustrate in a specific case the application of this general approach to the analysis of multicomponent mixtures. It is shown in this paper that iodine numbers obtained by NMR agree with those obtained by the classical titration method within two or three iodine numbers over a wide range of values. The effect of varying NMR instrumental parameter settings over a wide range has also been investigated and reported. In view of the results obtained in the present work, it appears that computers aided quantitative analysis using sophisticated analytical instrumentation such as NMR spectrometers, and should now be given serious consideration by many high volume, multicomponent analyses in the food, drug and chemical industries.