Infrared analysis of lecithin/sphingomyelin ratios.

A clinical evaluation of a quantitative infrared method for lecithin and sphingomyelin is described. The method incorporates techniques of computer-assisted infrared spectroscopy for both control of the microprocessor-based infrared spectrophotometer and for evaluation of the data. An advanced software package for quantitative infrared analysis, which can operate on a microcomputer, provides the possibility of complete automation of the analysis. Results of the analyses of amniotic fluids from 20 patients are presented. In general, the results of the analysis of the lecithin/sphingomyelin ratio by the infrared method correspond closely to those obtained by two-dimensional thin-layer chromatography on the same respective samples.