Comprehensive analysis of human sebum lipids by using GCxGC-HRTOFMS
Skin is an active metabolic tissue that synthesizes a variety of complex lipid compounds. Sebum, an oily material secreted by the skin, is known to provide a moisturizing effect, sunlight protection, and antibacterial protection for the skin surface. Sebum consists of a complex mixture of free fatty acids, squalene, cholesterol, wax esters, diacylglycerols and triacylglycerols. These species and their concentrations vary depending on skin conditions.
Lipid compounds are generally measured by using GC–FID, GC–MS or LC–MS. However, these methods are often unable to separate all of the individual compounds under the same measurement conditions. In addition, it can be difficult to definitively identify each lipid compound due to co-elution.
On the other hand, two-dimensional GC - high resolution time-of-flight mass spectrometry (GCxGC–HRTOFMS) is a powerful tool for identifying analytes in complex mixtures such as crude oils. The purpose of this work is the comprehensive detection and identification of lipid compounds in sebum by using GCxGC-HRTOFMS.
Samples were collected onto square aluminum sheets (3cm x 3cm) gently wiped across a human forehead for 2 minutes. This was repeated for a total of 3 sheets. The lipid compounds were then extracted with sonication from the aluminum sheets using a 3mL of a 50/50 volume solution of methanol/dichloromethane. Next, the extraction solution was centrifuged and the supernatant was concentrated to 200 μL. The resulting solution was analyzed using GCxGC–HRTOFMS and the conditions shown in table 1.