Researchers in New Zealand in the late 1980's used gas
chromtographic analysis to identify a range of unifloral honeys -
Tan, et al (1989) A chemical approach to the determination of
floral sources of New Zealand honeys. Journal of Apicultural
Research 28(4): 212-222.
 
The analysis technique is commonly referred to in New Zealand as
honey "finger printing", since the pattern of spikes on the
chromatograph for any particular honey source is unique to that
source.
 
The technique has been well-proved and overcomes a number of
problems with other types of honey source analysis (especially
pollen content analysis, where the pollen grains of some floral
sources have been found to be very under-represented).  However,
to my knowledge "honey finger printing" has so far not been
accepted by major world honey buyers.