This method uses the Thin Layer Chromatography (TLC)
for material and reagents .. see part one
Cut
the sheet to the required size white side up (be careful, the silica layer is
fragile, do not touch it with your fingers)
Two
centimeters (1 inch) from the bottom edge, draw a light line with a pencil,
draw on this line marks all minimum 2cm (fit based on test samples) see Figure
1 - Phase 1
Identify
the plate so no questionable (date, batch reference) drive the top edge (the
first centimeters)
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| Figure 1
Activation of the plate:
By
heating at 100 ° C (212 ° F) for one hour (domestic oven)
Choice of the compound
of reference:
In
the absence of pure products (difficult to obtain regard to the legislation)
Take
a lot that has been tested by an outside laboratory, reserve a part and keep in
the freezer) them split in aliquots of + / - 100mg
Preparation
of the samples:
Weigh
accurately about 10 mg of the test product (oil)
Dissolve
in 20 ml of ethanol to obtain a concentration of 0.5mg/ml
Adjust
the volume of ethanol by weighing (eg, weighing 10.5 mg = 21 ml of ethanol
Using
a capillary tube gently lay one µl of solution (0.5µg substance). Does not make craters
Successively
1μLde the
reference solution (spot A), 1 μL of test
solution (spot B) 2μL of the
test solution (spot C)….. (see Figure 1)
USE ONE CAPILLARY BY A SINGLE SPOT!
allow
to dry
Preparation
of the mobile phase (eluent)
Petroleum ether 60/90 (CAS 8032-32-4)
........ 80% v / v
Di-ethyl ether (CAS: 60-29-7.) ...................... 20% v / v
The
volume to prepare depends on the tank used, typically 50 ml is sufficient (40
ml petroleum ether 60/90 and 10 ml of diethyl ether)
Prepare a strip of absorbent paper (towel) with a width equal to a major
surface of the tank (or two fifths diameter if it is a round tank) See
Figure 2
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 |
| Figure 2
Pour the mobile phase in the tank, cover and let
stand 15 minutes to saturate
Place
the test plate in the tank (the side of the base line in the eluent)
the
solvent does NOT reach the baseline
Close
the tank
The
migration time depends on the temperature (not working at too high temperature)
Remove
the plate when the solvent front reaches approximately 2.5 cm (1 inch) from the
top edge of the plate
.
The
dry a few minutes with a hairdryer
Revelation
Prepare
10 ml of a solution composed of:
Fast
blue B salt (CAS: 5486-84-0 / C.I. 37175) .... 25 mg
0.1N
NaOH (CAS 1310-73-2) ........................... 10 mL
Spray
lightly and evenly on the plate (do not soak)
let
it dry
The
color is stable over time. For added security, a photo can be done, take care
to place a measuring stick in the field of the photo (further measures
maintaining the scale)
Using
a pencil,
Leading
the front line of solvent
Wrap
each spot as accurately as possible to conclusively identify (a1, a2, a3 ....
B1 b2 b3 ...)
Mark
the center
Measure
and record the following:
The
distance between the baseline and the solvent front D1(Figure 1)
The
distance between the baseline and the center of each spot D 2 (Fig. 1)
References
:
A qualitative and quantitative HPTLC densitometry method for the analysis
of cannabinoids in Cannabis sativa L.. - Issue 5 -
2009 - pp. 421-426Justin T. Fischedick - Ronald Glas - Arno
Hazekamp - Rob Verpoorte - Phytochemical Analysis - Vol. 20
F. Geiss, Die Parameter der
Dünnschicht-Chromatographie,
Verlag F. Vieweg & Sohn, Braunschweig, 1972
Méthodes recommandées pour
l’identification et l’analyse du cannabis et des produits du cannabis, Section
scientifique et du laboratoire, UNITED NATIONS OFFICE ON DRUGS AND CRIME Vienna 2010
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