Figure 9

Comparison between FTIR and TLC detection methods of clock-time dependent changes of lipid hydroperoxides in the lip. (A) Clock time dependent changes of infrared spectral ratio between the peroxide-related trans-alkene absorption at 968 cm^-1, [peroxide], and the triglyceride-related ester absorption at 1740 cm^-1, [ester]. The ratio was the highest at noon just before lunch. The subjects were two males in age 20s and 30s and the increase of the ratio at 12:00 clock time was significant (n = 4, p < 0.05) when compared with the ratio at 10:00 or 14:00 clock time. (B) Clock time dependent TLC patterns (right inserted figure; DMPD stained LOOH (left side) and charred TG (right side)) and [LOOH]/[TG] ratio changes (left inserted figure). The lip surface lipids were extracted as shown in Fig. 1(B) and developmental condition for TLC was the same as shown in Fig. 2. The subject was one male in age 30s. Both the clock time dependent patterns in FTIR and TLC were quite resembled, however, the experiment of (B) was done only in duplicate and the statistical consideration was avoided.