INTERACTIONS OF COSMETIC PIGMENTS WITH PRESERVATIVES 91 HO--••C-- OCH3 (b) • / II (a) (c) (d) O +D•O (C) (d) H•O (a) (ppm) Figure 6. ZH-NMR spectra ooe recovered M? that was incubated without pigment. HO-=•'•-- C-- OCH3 • •/ II (a) I (c) (d) O _ diminished •c) (d) (ppm) Figure 7. •H-NMR spectrum of MP that was recovered from incubation with ultramarine blue.

92 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS HO(e-'• COOCH3 (b) (d) (f) (a) (b) (f)(e) (d) (c) 1•0 1•0 1{50 8'0 •0 (ppm) (a) TMS go 6 Figure 8. •3C-NMR spectrum of recovered MP that was incubated with ultramarine blue. The next investigation was done to determine whether or not the disappearance of the phenolic hydrogen of MP would occur in the presence of other pigments. Disappearance of the phenolic hydrogen was also observed in the presence of titanium dioxide (A), titanium dioxide (R), and talc (Table V). Consistent with this change, it was found that the bactericidal activity of MP was decreased. In the cases of kaolinite and silica alu- mina, however, there was no disappearance of the phenolic hydrogen or loss of bacteri- cidal activity of MP. When BP was used in place of MP under the same experimental conditions, there was no disappearance of the phenolic hydrogen and no loss of bactericidal activity of BP with all the pigments used. On the basis of these NMR observations, it is assumed that the phenolic hydrogen of MP changed, but surroundings of the phenolic carbon were not changed by the treat- Table V Effects of Pigments on the Phenolic Hydrogen Signals and Bactericidal Activities of MP and BP MP BP Phenolic Phenolic hydrogen ID hydrogen ID Titanium dioxide (R) -- 10- 3 + 10- o Titanium dioxide (A) -- 10 -3 • 10 -2 q- 10 -ø Talc 10 -5 • 10 -4 q- 10 -ø Ultramarine blue -- 10- 5 + 10- 0 Kaolinite q- 10-• • 10 -ø + 10 -ø Silica alumina + 10 -ø + 10 -ø +: exist. -: disappear.