Mould growth on building materials - Statens Byggeforskningsinstitut

mycotoxins as the aflatoxins 403 . Engler et al 404 used the yeast Kluyveromyces marxianus
grown in microtitre plates for detection of TR by monitoring its expression of β-galactosidase.
An assay measuring protein translation inhibition have has reported by Yike et al 322 . This
assay has detection limits 20-400 times lower than cell cultures.
2.6.2 Sample preparation
The most time-consuming part of analysing for mycotoxins and other fungal metabolites, is
extraction and especially the sample clean-up.
2.6.2.1 Trichothecenes
TR range from polar compounds like nivalenol (NIV) extracted with methanol-water or acetonitril-water
mixtures to apolar compounds such as diacetoxyscirpentriol (DAS) and T-2 toxin
(T-2) extracted with mixtures of chloroform, dichloromethane and ethyl acetate. Thus no
method can provide full extraction (≈ > 80%) of all TR unless multiple extractions are performed
340 .
The MTR can be extracted using water-methanol to dichloromethane-methanol mixtures, but
the first mixture should extract fewer interfering components 405 .
At least one solid phase extraction (SPE) step has to be included before the TR can be detected.
Most successful are normal phases, such as silica gel, florisil, charcoal-alumina or
MycoSep columns 340,359 . Reversed phase has also been published 351 , 406 but due to the large
difference in polarity of the TR and the time-consuming evaporation of water these methods
have not been as popular as the normal phase ones. For the MTR the PEI silica has proven
to be superior, as it selectively removes the spiriocyclic drimanes, phenolic compounds and
the brownish gum always present in extracts from Stachybotrys 405,407 .
For the polar TB immunoaffinity clean-up is also widely used, as they are soluble in the water-acetonitrile
mixtures used for loading immunoaffinity columns 340,390 , and can be detected
using HPLC with UV detection.
2.6.3 Detection of mycotoxins in air and settled dust
To estimate the human exposure to mycotoxins, these have to be measured and quantified
directly in air samples or in settled dust. But as spores and airborne dust contain interfering
components and the spore concentration is very low 408 (usually