When an equal volume of ultrapure water was added to the raw
acetonitrile extract as proposed by Mawn et al. (2005), the solid
matter precipitated out of the solution and after centrifugation, the
signals of aliphatic hydrocarbons disappeared from the GCeMS
scan. However, even after this treatment, precipitation of some real
extracts was observed to continue during the storage at 4 C in a
HPLC autosampler. For this reason, lowered temperature (10 C)
was applied during centrifugation of diluted extracts.