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n-heptadecane was added as a standard, and the powder extracted twice with 10 ml of a mixture of
chloroform and methanol (2+1) with supersonic agitation. After each extraction the mixture w
centrifuged to remove the suspended solid. The extract was concentrated in a rotary evaporator and
finally dried in a gentle stream of nitrogen. Trimethylester and ether derivatives were prepared by
heating aliquots with excess N,O-bis(trimethylsilyl)trifluoroacetamide.

The GC/MS analysis was performed on a Pye 204 GC in conjunction with VG double focusing
magnetic sector mass spectrometer and a Finnigan INCOS 2300 data system. The transfer line was
maintained at 350°C, the ion source at 300°C and the electron impact ionization took place at 70 eV.
The total ion current of a potsherd extract is shown in figure 5.15.

Figure 5.15.
Total Ion Current Chromatogram of the Lipids
from a Potsherd from a Late Saxon Ditch (ref 12)

It is seen that an interesting selection of lipid materials has been extracted from the potsherd. according
to the authors, the technique is now a routine procedure for ceramic materials found at the various
archaeological site under investigation at that time.