REV. CHIM. (Bucharest) ♦ 63 ♦ No.3 ♦ 2012http://www.revistadechimie.ro294
Other major cannabinoid present in cannabis products, namely cannabidiol may also suffer changes depending on
storage conditions. In this respect, under acidic conditions it may transform into Δ9–THC by acid-catalyzed cyclization
and, in the presence of oxygen, is oxidized to monomeric and dimeric hydroxyquinones .
Although the cannabinoids stability was intensively
studied previously, most of the researches were done on
pure solutions, which can have a different behaviour
towards actual cannabis products. Therefore, the objective
of this paper is to explore experimentally the influence of
storage conditions such as temperature and light on the
stability of the major cannabinoids in the cannabis oil.
Chemicals and reagents
All chemicals and reagents used for samples preparation
and analysis were of analytical grade from Merck
(Darmstadt, Germany). The etalons of Δ9–tetrahydro-
cannabinol (Δ9–THC), cannabidiol (CBD), and cannabinol
(CBN) were purchased from Switzerland. The ultrapure
water used in HPLC analyses was prepared in-house using
a Millipore system, model Milli-Q Integra 3.
Cannabis oil samples
Cannabis oil from two different seizures (marked with
symbols U1 and U2) made by criminal prosecution
authorities from Romania and provided by Central
Laboratory for Drug Analysis and Profiling were subject to
experimental investigation. The samples of cannabis oil
were supplied in small bottles and have a black-brown
colour and a high consistency comparable to that of a paste.
The samples were stored in the darkness at 4°C and in the
laboratory light at 22°C for four years. At regular intervals,
namely at every three months, samples were taken for
analysis in order to determine the content of their major
cannabinoids (Δ9–THC, CBD, and CBN).
The procedure that led to the sample preparation for
analysis consisted of extracting 0.05 g of cannabis oil in 20
mL of a methanol-chloroform (9:1, v/v) mixture. Thus, the
samples were shaken for 30 min and then placed in an
ultrasonic bath at ambient temperature for 15 min in order
to increase the cannabinoids extraction rates. The extracts
were filtered and some aliquots (0.6 mL) of the filtrates
were transferred to a 4 mL vials and then evaporated to
dryness by oven evaporation, only up to 80°C for prevention
of any decomposition reactions. Then, the vials were put
into a heating unit at 220°C for 12 min when the traces of
tetrahydrocannabinolic acid (THCA) are decarboxylated.
Decarboxylation is particularly required for the
determination of the entire content of Δ9–THC of the
sample. Before analyses, the residues were extracted in
1.5 mL extraction solvent (methanol-chloroform 9:1, v/v).
After this, the samples were subject to analyses of the
major cannabinoids content (Δ9–THC, CBD, and CBN) .
Extracts obtained by procedure described above have
been subject to analytical investigations through
instrumental methods (GC–FID – Gas Chromatography–
Flame Ionization Detector and HPLC – High Performance
Liquid Chromatography) in order to find out the content in
major cannabinoids (Δ9–THC, CBD, and CBN).
GC–FID analyses were carried out on a 7890A gas
chromatograph with a flame ionization detector.
Separation was achieved on a fused silica capillary column
(HP-5MS, 30 m×0.32 mm i.d., 0.25μm film thickness, J&W
Scientific, Folsom, CA, USA). Temperature program: 150°C
hold for 1 min, 10°C/min to 280°C, hold for 5 min. The
injection port and interface temperature were 250°C and
300°C, respectively. Split injection mode was used (20:1)
and hydrogen, with a flow rate of 30 mL per min, was used
as carrier gas .
HPLC analyses were carried out on an Agilent 1100
Series HPLC chromatograph equipped with a quaternary
pump, autosampler, column oven and diode-array detector
(DAD) UV Lamp ON (223 nm). Chromatography was
achieved on a 250 mm × 4.6 mm i.d., 5 μm Hypersil ODS
column. The HPLC operates with constant flow at 1 mL
mobile phase (acetonitrile 37.5% and ultrapure water) per
Results and discussions
GC–FID and HPLC chromatograms revealed a very high
content of ΔΔ
Δ9–THC in the cannabis oil samples and
subsequently, a very high potency of these type of cannabis
product compared to other cannabis products such as
herbal cannabis and cannabis resin. The difference
between the two samples regarding their potency is
significant and comes probably from the use of different
procedures for their obtaining. The difference could be due
to the type of solvent used for extraction, number of
extractions, conditions of extractions etc. These results
indicate, on the one hand, that the samples were prepared
in different clandestine laboratories, improvised by different
drug traffickers and, on the other hand, that the samples
went through different routes of trafficking originating from
different geographical areas. Following a detailed analysis
of such data, the prosecution authorities could identify
trafficking routes, and finally the places where this type of
drugs were made.