PENETRABILITY OF OILS IN HAIR 177 [Add] [[Add]:427.580] - 126.67 Scale: 10pro (Io9) Untreated: Coconut oil distribution [Add] [[Add]:427.580] - 126.67 Cts: 85833 Max: 28 Scale: 10prn Coconut oil distribution [Add] [[Add]:427.580_'l- 126.67 Ct$: 132750 Max: 56 Scale: 10pro (log) Coconut oil distribution [Add] [[Add]:427.580] - 126.67 Cts: 229094 Max: 60 Scale: 10pm coconut oil distribution Figure 6. Imaging the presence of coconut oil at mass number ! 26.67 m/z (one of the characteristic positive ions of coconut oil) in the surface of (a) untreated and (b-d) coconut-oil-treated cross-sectioned hair fibers. Characteristic negative ions of pure mineral oil. The negative spectra also contain a series of peaks with a 14Da interval in the mass range above 100 m/z. A representative negative ion mass spectrum of mineral oil is shown in Figure 7b. Mass spectra of characteristic positive ions of untreated hair: controls for coconut-oil-treated hair. The TOF-SIMS spectra were obtained from the surface of the cross sections of untreated hair fibers and showed no peaks corresponding to the mineral oil. The spectra were dominated by hydrocarbon and sodium peaks and showed contamination from coconut oil and polydimethysiloxane (Figure 8). The spectra do not contain any of the high-mass peaks observed in the coconut oil mass spectra.

178 JOURNAL OF COSMETIC SCIENCE BP1.TDC + Ions 1211,m• 2610D10 cts o 41 4O Maas [m/z] BP1.TDC + Ions t2t1..'n 2610010 cts 14000' '• 1 137 ,, ].. II !.!,l..,ILl, i.,,,,, • ,,.,. , 149 140 160 1•0 • l•zl -1 200 220 240 260 280 BPl.'T13• + Ions 121Hm 2610010 cts • • a• • M•neral off Figure 7a. Spectra of positive ions of mineral oil deposited on a silicon wafer, including characteristic positive ions of mineral oil. Characteristic positive ions of mineral-oil-treated hair. The positive spectra obtained from the surface of the cross sections of hair fibers treated with mineral oil are similar to the spectra of the untreated hair (Figure 9). No mineral oil was detected in the treated hair. However, coconut oil and polydimethylsiloxane peaks were observed in the high-mass range, similar to observations made for the untreated hair fiber. This indicates that these hair fibers had been exposed to coconut oil as well as silicones and surfactants. TOF-SIMS IMAGING OF MINERAL OIL IN HAIR BY CHARACTERISTIC POSITIVE IONS The positive ion at mass number 361.26 is unique to mineral oil, and was used to map its distribution in cross sections of untreated and mineral-oil-treated hair fibers (Figure 10a,b). The image of the untreated hair fiber (Figure 10a) shows essentially nothing. For the mineral-oil-treated fiber cross section, there is a slight increase in the number of