NMR ANALYSIS OF COSMETIC INGREDIENTS 5O9 e o II H 0 Figure 1. Spectrum o{ acetic acid (the separation between hydroxyl and metlay] protons is caused by aleshielding) The three hydrogens on the methyl groups are more shielded and require a higher magnetic field in order for absorption and resonance to occur. INSTRUMENTATION A high resolution NMR spectrophotometer* is composed of five major units (2): 1. A stable magnet strong enough to generate a homogeneous magnetic field of 14,092 Gauss between its pole faces. 2. A means of varying the magnetic field over a narrow milligauss range. This is achieved by passing a direct current through coils surrounding the sample. 3. A radio frequency oscillator-supplying the radio frequency signal nec- essary to elevate the nuclei from the ground state energy level. 4. A radio frequency receiver to detect energy absorption by the sample. 5. A recorder and integrator. QUANTITATIVE ANALYSIS The spectrmn resulting from the absorption of eleetromagnet!c energy can be used to determine the nature of the chemical environment, i.e., the num- ber and location of protons in a molecule. The area under each absorption band is directly proportional to the number of protons which absorb at that frequency. Hydroxyl, olefinie, earboxyl, aldehydie, ester, and ethoxy protons, because of their proximity to an electron-withdrawing substituent, oxygen, *The instrument used in this work was a Model R-24, Perkin-Elmer Corp., Norwalk, Conn. 06852.

510 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS OLEYL ALCOHOL E•UAI 101•1 IV = (AREA OF OLEFhl PROTONS) (MMOLES CHC13) 12,69 (AREA OF CHC13) (SAMPLE WT,) SIRUCIURE CH3 (CH2) 6 CH 2 CH:CH CH 2 (CH2) 6 Ch 2 OH G F E g E F D C b i OLLYL ALCOHOL Figure2. Spectrum of oleyl alcohol and ealctdation of iodine value (CCi• as solvent) EQUATIOI'I I d I SAP VALUE : (AREA OF CH Oil TIlE O) ([qPiOLLS CHCis) (56,1) (SAgPLE WEI6HI) (AREA OF CHC137 E D C CH3(CH 2 ) 13CH2/C',• C•3 OCH B '"% E II • r I I I I I I f ISOPROPYL PALMITATE-STRUCTURE Figure 3. Spectrum of isopropyl palmitate and calculation of ester value (CCh as solvent)