Keiichi Honda

Computer-Assisted Analysis system of 13C-NMR Spectra Desinged for Composition Determination of Cosmetic Products (II)

An attempt was made at composition analyses of hair dye products and foundations by utilizing computer-assisted analysis system of 13C-NMR (CMR) which had previously been developed in our laboratory. The system consists of the measurement of 13C-NMR spectrum of an unknown mixture and of subsequent computer analysis of the spectrum.Despite the facts that hair dye products are usually composed of both large amounts of various surfactants and small quantities of labile oxidizing dyes susceptible to air and that the foundations being diverse in formulation, on the other hand, contain a lot of inorganic pigments which are not amenable to CMR, analytical results on organic components in these cosmetic products were found satisfactory, thereby indicating, when our earlier work is taken into account, that this system would be successfully applicable to composition analyses of a variety of organic mixtures as well as cosmetics.

Computer-Assisted Analysis System of 13C-NMR Spectra Designed for Composition Determination of Organic Mixtures

We have developed a new system designed for composition analysis of mixtures of organic compounds.This system consists of the measurement of 13C-NMR (CMR) spectrum of an unknown sample (usually a mixture of manifold compounds) and of subsequent computer analysis of the spectrum. The analyses of CMR spectra are carried out on the basis of the standard spectra of authentic compounds which are already stored in floppy disks (data base).The first step of the procedure is to search candidate compounds that are deemed to be present in the sample, The second step is the signal assignment, which is conducted accoding to multiple regression analysis, and the final step of simulation which is made so as to minimize the sum of the square of error (difference between the observed signal intensity and the calculated one) gives the relative composition of each component.In the present study, we have applied this system to the composition analysis of cosmetic products such as lipsticks and creams, and the results demonstrated the usefulness of this new system for both qualitative and quantitative determination of various mixtures.This system requires little or no separation process nor technical knowledge of the operator, and is also applicable to a variety of scientific fields other than cosmetic research. The system, however, is not suitable for the analysis of trace components or polymers because of the insufficient sensitivity of CMR spectroscopy.