This document summarizes a study that evaluated the linearity of using FTIR to quantify dimethicone in lotion formulations. Various amounts of dimethicone were spiked into placebo lotions. The samples were extracted with hexane and analyzed via FTIR spectroscopy by measuring absorbance at 1260 cm-1, which is characteristic of dimethicone. Absorbance values increased linearly as dimethicone amounts increased from 0-120%, demonstrating the method can deliver quantitative, dose-dependent results for dimethicone. The linear regression analysis showed an R2 value of 0.9992, indicating acceptable predictability of the method.

1. Quantitation of Dimethicone in Lotionized Formulations Using Liquid Flow Cell and FTIR Part 1: Linearity Studies Luke Shokere, Ph.D.

5. Table 1. Sample preparation. 1.80 3928 72 120 1.65 3934 66 110 1.50 3940 60 100 1.35 3946 54 90 1.20 3952 48 80 0 4000 0 0 Dimethicone Placebo Dimethicone Sx wt. % wt. mg mg % Normal

6. Figure 1a. FTIR spectral results for the 1260cm -1 peak. Blue 120%; Red 110%; Black 100%; Brown 90%; Green 80%; Black, Placebo (no peak).

7. Figure 1b . Peak integration process .

8. Figure 2. Linearity plot.

9. Table 2. Peak integration absorbance results 0.1922 120 0.1706 110 0.1516 100 0.1302 90 0.1077 80 0.0000 0.0 Absorbance Dimethicone FTIR % Normal