Dimethicone by Reversed Phase HPLC/ELSD

Dimethicone standard was separated by reversed phase HPLC/ELSD, but separation from a hand lotion was only partly successful due to interferences.

Dimethicone, Alltech Application Note 0048E, July 7, 2000.

Dimethicone, a silicone derived oil, is commonly used in cosmetics, hair care products and pharmaceutical processing. Its analysis is difficult and is usually performed by FT-IR.

A dimethicone standard and a sample of hand lotion containing dimethicone were extracted with hydrochloric acid and methylene chloride. The organic phase of the standard was separated in 20 minutes by gradient elution with acetontrile/chloroform on an Alltima C8, 5µ, 150 x 4.6mm reversed phase HPLC column (Part No. 88072) using water. Peaks corresponding to dimethicone were detected by evaporative light scattering using an Alltech 500 ELSD (Evaporative Light Scattering Detector).

Separation of the dimethicone from the hand lotion was not entirely successful with interfering sample components co-eluting with about half of the dimethicone.

In ELSD, the mobile phase is first evaporated. Solid particles remaining from the sample are then carried in the form of a mist into a cell where they are detected by a laser.