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Figure 1:
Potency testing of marijuana using an Rxi®-5Sil MS GC column results in higher sensitivity for all target analytes.
min.
3.6
3.8
4.0
4.2
4.4
4.6
4.8
5.0
5.2
5.4
1
2
3
Standard
Sample
GC_GN1156
Column
: Rxi®-5Sil MS, 15 m, 0.25 mm ID, 0.25 µm (cat.# 13620);
Injection
: Inj. Vol.: 1 µL split (split ratio 20:1); Liner: Sky™ 4.0 mm ID single taper/gooseneck inlet liner w/wool (cat.# 23303.5); Inj. Temp.: 250 °C;
Oven:
Oven Temp: 200 °C (hold 0 min.) to 300 °C at 15 °C/min. (hold 0 min.);
Carrier Gas
: H
2
, constant pressure (7 psi, 48.3 kPa); Temp.: 200 °C; Dead Time: 0.6 min. @ 200 °C;
Detector
: FID@ 300 °C; Make-up Gas
Flow Rate: 45 mL/min.; Make-up Gas Type: N
2
;
Instrument
: HP5890 GC;
Notes
: Blue trace = cannabinoids standard (cat.# 34014) diluted to 100 µg/mL in isopropyl alcohol.; Red trace = extracted marijuana sample;
Sample extraction: Weigh 0.2 g of sample into a 40 mL VOA vial, add 40 mL of isopropyl alcohol, shake for 5 minutes, and allow sample to settle.; Quantification: Potency values (weight%) were based on a 1-point
standard curve using the standard show above.
Peaks
RT (min.)
Conc.
(wt.%)
1. CBD
4.035
0.0
2. THC
4.524
3.6
3. CBN
4.840
0.3
Figure 2:
Ultra Aqueous C18 columns easily separate THCA, which is used to determine marijuana potency when testing by LC.
1.5
2.0
Standard
Sample
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
min.
1
2
3
4
LC_GN0530
Column
: Ultra Aqueous C18 (cat.# 9178312); Dimensions: 100 mm x 2.1 mm ID; Particle Size: 3 µm; Pore Size: 100 Å; Temp.: 30 °C;
Sample:
Inj. Vol.: 10 µL;
Mobile Phase:
A: Water + 10 mM potassium phosphate
(pH = 2.5), B: Methanol; Flow: 0.4 mL/min.; Gradient (%B): 0 min. (80%), 1.0 min. (80%), 5.0 min. (95%), 6.0 min. (95%), 6.1 min. (80%), 8.0 min. (80%);
Detector
: UV/Vis @ 220, 4 nm; Cell Temp: 40 °C;
Instrument
: Shimadzu UFLCXR;
Notes
: Blue trace = cannabinoids standards (cat.#s 34014 and 34093) diluted to 100 μg/mL in isopropyl alcohol; Red trace = extracted marijuana sample; Sample extraction: Weigh
0.2 g of sample into a 40 mL VOA vial, add 40 mL of isopropyl alcohol, shake for 5 minutes, and allow sample to settle. Dilute extract 10x with isopropyl alcohol.; Quantification: Potency values (weight%) were based
on a 1-point standard curve using the standard show above.
Peaks
RT (min.)
Conc.
(wt.%)
1. CBD
2.507
0.1
2. CBN
3.632
0.0
3. THC
3.977
0.5
4. THCA
5.364
4.5
Rxi®-5Sil MS Columns
(fused silica)
(low polarity Crossbond® silarylene phase; similar
to 5% phenyl/95% dimethyl polysiloxane)
Description
temp. limits
cat.#
15m, 0.25mm ID, 0.25µm
-60 to 330/350°C 13620
similar
phases
DB-5ms, VF-5ms, CP-Sil 8 Low-Bleed/MS,
DB-5ms UI, Rtx-5Sil MS, ZB-5ms, Optima 5ms,
AT-5ms, SLB-5ms, BPX-5
Ultra Aqueous C18 Columns
(USP L1)
Description
cat.#
3µm Columns
100mm, 2.1mm ID
9178312
3µm Columns
100mm, 2.1mm ID
(with Trident Inlet Fitting)
9178312-700
similar
phases
AQUA C18, Aquasil C18, Hypersil Gold AQ,
YMC ODS-Aq
Acknowledgment
Randy Hoffman, a Police Evidence Technician at The
Pennsylvania State University (PSU), supplied the
seized marijuana samples while overseeing their han-
dling. Frank Dorman at PSU provided access to the
samples and assisted with prep.