87
GC COLUMNS |
APPLICATION-SPECIFIC COLUMNS
Foods, Flavors, & Fragrances
Residual Solvent Analysis for Cannabis Concentrates
Rxi®-624Sil MS Columns
(fused silica)
(midpolarity Crossbond® phase)
• Low-bleed, high-thermal stability column—maximum temperatures up to 320 °C.
• Inert—excellent peak shape for a wide range of compounds.
• Selective—G43 phase highly selective for volatile organics and residual solvents,
great choice for USP<467>.
• Manufactured for column-to-column reproducibility—well-suited for validated
methods.
Rxi®-624Sil MS (G43) Structure
x
Si
O
(CH
2
)
3
CH
3
CH
3
CH
3
Si
O
R
O
CH
3
CH
3
Si
94%
y
CH
3
CH
3
Si
C N
similar phases
DB-624, VF-624ms, CP-Select 624 CB
20-Meter
30-Meter
60-Meter
75-Meter
105-Meter
ID df
temp. limits cat.#
price
cat.#
price
cat.#
price
cat.#
price
cat.#
price
0.18 mm 1.00 µm -20 to 300/320 °C 13865
0.25 mm 1.40 µm -20 to 300/320 °C
13868
13869
0.32 mm 1.80 µm -20 to 300/320 °C
13870
13872
0.53 mm 3.00 µm -20 to 280/300 °C
13871
13873
13874
13875
Similar to: (6%-cyanopropylphenyl)-methylpolysiloxane
1
2
3
4
5
6 7
8
9
10
11
12
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
Time (min)
Residual Solvents in Cannabis Concentrates on Rxi®-624Sil MS by Headspace–Full Evaporation
Technique (HS-FET)
GC_FS0517
Peaks
t
R
(min)
1. Isobutane
0.910
2. Butane
0.996
3. Methanol
1.112
4. Pentane
1.508
5. Ethanol
1.545
6. Acetone
1.795
7. Isopropanol
1.891
8.
n
-Hexane
2.412
9. Chloroform 2.962
10. Benzene
3.213
11. Heptane
3.363
12. Toluene
4.135
Column
Rxi®-624Sil MS, 30 m, 0.25 mm ID, 1.40 µm (cat.# 13868)
Sample
Residual solvent mix
Diluent:
Dimethyl sulfoxide (DMSO)
Conc.:
500 ppm (For the HS-FET technique, 10 µL of a 1,000 µg/mL
standard was placed into a 20 mL headspace vial to represent a
500 ppm sample concentration, assuming a 20 mg sample.)
Injection
headspace-loop split (split ratio 10:1)
Liner:
Sky® 1.0 mm ID straight inlet liner (cat.# 23333.1)
Headspace-Loop
Instrument:
Tekmar HT3
Inj. Time:
1.0 min
Transfer Line Temp.: 160 °C
Valve Oven Temp.:
160 °C
Needle Temp.:
140 °C
Sample Temp.:
140 °C
Platen temp
equil. time:
1.0 min
Sample Equil. Time: 30.0 min
Vial Pressure:
20 psi
Pressurize Time:
5.0 min
Loop Pressure:
15 psi
Loop Fill Time:
2.0 min
Oven
Oven Temp.:
35 °C (hold 1.5 min) to 300 °C at 30 °C/min (hold 2.0 min)
Carrier Gas
He, constant flow
Linear Velocity:
80 cm/sec
Detector
FID@ 250 °C
Make-up Gas
Flow Rate:
45 mL/min
Make-up Gas Type: N
2
Hydrogen flow:
40 mL/min
Air flow:
450 mL/min
Data Rate:
20 Hz
Instrument
Agilent/HP6890 GC
Notes
The butane used for standard preparation was a mixture of
butane and isobutane in an unknown ratio. The concentrations of
butane and isobutane should be considered approximate, but do
not exceed 500 ppm for either component.
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