POTENTIALITIES OF INFRARED ANALYSIS OF LIPIDS OF THE BRAIN

Author Institution: Laboratories of Philadelphia, General HospitalPotentialities of infrared analysis of lipids of the brain are discussed. Cephalin and lecithin, on one hand, and sphingomyelin and cerebrosides, on the other, can be distinguished by the spectra in the $6\mu$ region; the former show a $C-O$ ester band at $5.75 - 5.80\mu$, the latter the amide vibrations at 6.10 and $6.44\mu$. The differences between cephalin and lecithin or cholesterol and cholesteryl esters in the $9 - 10\mu$ region are useful for analytic purposes. Spectra of ether compounds related to lipids (cholin, inisotol, etc.) are demonstrated. It is concluded that infrared analysis will be very advantageous for the study of lipids of the brain. The necessity for better fractionation methods is stressed. Until this can be accomplished, infrared spectroscopy of dried-frozen brain sections (before and after extraction) is useful for establishment of differences under various conditions, such as distribution in various parts of the brain, various stages of development, etc