Determination of ergosterol in organic dust by gas chromatography-mass spectrometry.

A gas chromatographic-mass spectrometric method was developed for the determination of ergosterol in organic dust. Samples were hydrolyzed under alkaline conditions, and the hydrolysate was extracted, purified on a silica-gel column, and subjected to derivatization. The limit of detection of the trimethylsilyl ether derivative of ergosterol was approximately 10 pg and that of the tert.-butyldimethylsilyl ether derivative was approximately 20 pg (injected amounts). House dust contained 6-45 micrograms ergosterol/g and air from a pig barn contained 0.2-0.3 ng ergosterol/liter. The proposed method can be used as a complement or alternative to microscopy and culturing for measuring fungal biomass in air-borne organic dust.