Health Canada Resource on THC analysis
COMMUNITY METHOD FOR THE QUANTITATIVE DETERMINATION
OF DELTA-9 THC (TETRAHYDROCANNABINOL) IN CERTAIN VARIETIES OF
1. Purpose and scope
This method permits quantitative determination of delta-9 tetrahydrocannabinol
(delta-9 THC) in certain varieties of hemp Cannabis sativa L.)
for the purpose of checking that the conditions laid down in
Article 3 (1) of Regulation (EEC) No. 619/71 are fulfilled.
Quantitative determination of delta-9 THC by gas chromatography
(GC) after extraction with a suitable solvent.
-- gas chromatography equipment with a flame ionization detector,
--glass column 2,50 m long and 3,2 mm in diameter (1,8")
packed with a suitable support impregnated with a stationary
phase phenyl-methyl-silicon (e.g. OV 17 at 3 %).
4. Sampling and reduction of sample
In a standing crop of a given variety of hemp, take not less
than 500 plants, preferably at different points but not from
the edges of the crop. Samples should be taken during the day
after flowering has finished.
The pooled samples should be representative of the lot.
The plant material is then left to dry at ambient air temperature.
Reduce the sample, obtained as described, to 500 stalks; the
reduced sample should be representative of the original sample.
Divide the reduced sample into two portions.
Send one portion to the laboratory which is to determine the
delta-9 THC content. Keep the other portion for counter-analysis
-- petroleum ether (40)/65°), or a solvent of comparable
-- tetrahydrocannabinol (delta-9 THC), pure for chromatographic
-- solution of 0,1% (w/v) androstene-3-17-dione in ethanol, pure
for chromatographic purposes.
6. Preparation of test sample
For the purposes of delta-9 THC determination, retain the upper
third of the plants in the portion of sample received. Stems
and seeds must be removed from the plant material retained.
Dry the material in an oven, without exceeding 40°C, to obtain
a constant weight.
Reduce the material obtained as described in point 6 to a semi-fine
powder (sieve of 1000 meshes per cm2.
Take 2,0 g of well-mixed powder and extract with 30-40 ml petroleum
ether (40-65°C). Leave for 24 hours, then shake in a mechanical
shaker for one hour, and then filter. The extraction process
is carried out twice under the same conditions. Evaporate the
petroleum ether solutions to dryness. Dissolve the residue in
10.0 ml of petroleum ether. The prepared extract is used for
quantitative analysis by gas chromatography.
8. Quantitative analysis by gas chromatography
(a) Preparation of assay solutions
The extraction residue dissolved in 10.0 ml of petroleum ether
is subjected to quantitative analysis to determine the delta-9
THC content. This is performed with the aid of an internal standard
and calculation of the peak areas.
Evaporate to dryness 1,0 ml of the petroleum ether solution.
Dissolve the residue in 2,0 ml of a solution of 0,1% androstene-3-l7-dione
in ethanol (internal standard with a retention time distinctly
higher than that of other cannabinoids, and in particular twice
that of delta-9 THC).
0,10, 0.25, 0,50, 1,0 and I,5 mg of delta-9 THC in 1 ml of a
solution of 0,1% androstene-3-l7-dione in ethanol.
(b) Experimental conditions
|Nitrogen flow rate:
|Hydrogen flow rate:
|Air flow rate:
||1 ml of the final ethanol solution.
The relative retention time of delta-9 THC is calculated in
relation to the andostene.
9. Expression of the results
The result is expressed in g of delta-9 THC per 100 g of the
laboratory sample dried to constant weight. The result is subject
to a tolerance of 0,03g per 100g.