The use of TSP Py-GC–MS, in combination with FTIR spectroscopy,
has allowed Canadian amber specimens to be more accurately
categorised. Analysis of the amber from the 11 deposits in Canada
showed that they represent three different classes: Class Ib (based on
regular-labdanes), Class Ic and Class Id (both based on enantiolabdanes).
Different formswere foundwithin the Class Ib and Icambers,
based on the presence and absence of self-crosslinking and free succinic
acid. Key macromolecular structural differences which affect the classification
of amber from different deposits include: macromolecular
structures based on regular- versus enantio-polylabdanoids,
crosslinking of the macromolecular structure (via succinic acid or selfcrosslinking),
and the esterification of non-polymerisable terpenoids
to functional groups on the macromolecular structure. Other compositional
differences included the presence of callitrisic acid (and diagenetic
compounds thereof) in all Class Ib ambers, but not in Class Ic or Class
Id specimens; and free succinic acid,whichwas identified in all six Class
Ib form 1 specimens and the single Class Ic form 1 specimen.
Crosslinking of the macromolecular structure has now been shown
to occur within all four Class I amber subclasses. The identification of
crosslinked fragments in amber specimens using TSP Py-GC–MS has
allowed for the more accurate interpretation of the accompanying
FTIR spectra. This has increased the usefulness of the technique in differentiating
between amber specimens.
Archaeological beads and fragments from a Thule site at Lake
Hazen on Ellesmere Island were determined to belong in Class Id.
The composition of these amber objects compares well to reference
material found in the vicinity. Beads and bead fragments from
two other Thule sites on Cornwallis Island and Banks Island were determined
to belong in Class Ib form 1. To date, the only reference
specimens belonging to this type that have been thoroughly
characterised originate from Cedar Lake and Grassy Lake. As reference
amber specimens from more deposit sites are studied, continuation
of comprehensive characterisation will be of great use in
investigating the deposit site origin of amber objects recovered
from archaeological sites across the country.