Materials
Human head lice (Pediculus humanus capitis) used in this work were received as untreated live head lice collected from infested patients and shipped the day of collection at room temperature conditions. Head lice were stored refrigerated for several hours prior to testing.
Three different extraction solvents were used:
50/50 w/w isopropyl myristate/decamethylcyclopentasiloxane (cyclomethicone D5) – (IPM/D5)-subject product
Iso-octane – a laboratory determined optimal extraction solvent for hydrocarbons
50/50 methanol/water - control
Sample Preparation
Ten head lice (per sample) were transferred individually with tweezers to clean empty 350-μL glass GC vial inserts. Specimens were covered with 80 μL of any of the three extraction solvents then allowed to incubate at room temperature for 10 minutes. The samples were then mixed by aspiration. Solvent samples containing the extracted lice cuticle hydrocarbons (CHCs) were transferred to a new unused insert contained in a 2-mL crimp top vial which was subsequently sealed and held for later analysis.
Gas Chromatography
A gas chromatograph equipped with a flame ionization detector (GC/FID) was used to determine the presence of hydrocarbons in the three head lice extracts. A standard containing a series of known hydrocarbons (C21-40) was used for qualitative sample comparison.
BMC Dermatol. 2012;12(15) © 2012 BioMed Central, Ltd.
