Determination of ergosterol on mouldy building materials using isotope dilution and gas chromatography-tandem mass spectrometry.

Ergosterol content of building materials was quantified using gas chromatography-tandem mass spectrometry (GC-MS- MS) in an ion trap with external ionisation. Hydrolysing the samples by classic extraction at 85 8C for 90 min in vials was 2 faster, more precise and safer than microwave assisted extraction. (4- H )ergosterol was synthesised and used as internal 2 standard, giving method standard deviation of 5-10% from 10 to 30 ng to 10-15 mg ergosterol in the sample. The use of GC-MS-MS meant that no solid-phase extraction clean-up was needed, so one person could easily prepare 40-80 samples per day. © 2000 Elsevier Science B.V. All rights reserved.