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Flavonoids… The Next Routine Cannabis Test?

17 Jun 2021

Hemp/cannabis are chemically complex matrices containing a wide-array of bioactive compounds, whose synergistic interactions give the plant its therapeutic effects. Flavonoids are a group of compounds found in hemp/cannabis and account for about 2.5% of the dry weight of the flowers and leaves.1 Flavonoids are antioxidant rich and can effect flavor profiles of foods. Hemp/cannabis also have some unique flavonoids that cannot be found in any other plants including cannflavin A, cannflavin B, and cannflavin C.

Routine testing in cannabis labs typically includes potency testing for phytocannabinoids and terpenes, but oftentimes doesn’t include flavonoid testing. Flavonoids are ubiquitous in hemp/cannabis and, like terpenes, contribute to the overall aroma and flavor of the plant. Herein, a method to detect flavonoids in hemp flower has been developed.

Since there are many naturally occurring flavonoids, a literature search was performed in order to compile a list of flavonoids most commonly detected in hemp/cannabis. A total of 19 flavonoids were identified as both analytes of interest and commercially available for purchase. Some of the desired compounds were difficult to procure, such as cannflavin C, but these compounds may become more readily available as flavonoid analysis in hemp/cannabis becomes more popular.

For analysis by LC-MS/MS, each compound was tuned and optimized for detection. Of the 19 analytes of interest, there existed three groups of isobars which required chromatographic separation for analysis. These groups are color coded in the compound table below and the critical separation of these compounds can be seen in the solvent chromatogram. This method has a 7 minute cycle time, allowing for rapid sample throughput.

Column

Raptor Biphenyl (cat.# 9309A12)

Dimensions:

100 mm x 2.1 mm ID

Particle Size:

2.7 µm

Pore Size:

90 Å

Guard Column:

Raptor Biphenyl EXP 5 mm, 2.1 mm ID, 2.7 µm (cat.# 9309A0252)

Temp.:

30 °C

Diluent:

60/40 Water/Methanol

Inj. Vol.:

2 µL

Mobile Phase

 

A:

Water, 0.1% formic acid

B:

Methanol, 0.1% formic acid

 

Time (min)

Flow (mL/min)

%A

%B

0.00

0.5

60

40

4.00

0.5

0

100

5.50

0.5

0

100

5.51

0.5

60

40

7.00

0.5

60

40

Detector

MS/MS

Ion Source:

Electrospray

Ion Mode:

ESI+/ESI-

Mode:

MRM

Instrument

UHPLC

 

 

Analyte

Retention Time (min)

Precursor Ion

Product Ion 1

Product Ion 2

Product Ion 3

Polarity

1

Orientin

1.47

449.0

329.1

299.1

431.0

+

2

Vitexin

1.83

433.0

313.1

283.0

415.1

+

3

Rutin

1.90

609.1

300.1

301.0

271.0

-

4

Quercetin-3-D-glycopyranoside

2.01

463.1

300.0

301.0

271.0

-

5

Isovitexin

2.02

433.4

283.0

313.1

337.0

+

6

Luteolin-7-O-glucuronide

2.22

463.0

287.1

153.2

135.1

+

7

Fisetin

2.44

285.0

135.0

121.0

163.0

-

8

Apigenin-7-O-glucuronide

2.66

447.0

271.1

153.2

119.1

+

9

Quercetin

2.75

301.0

151.0

179.0

107.0

-

10

Luteolin

2.92

285.0

133.0

151.0

175.0

-

11

Kaempferol

3.14

285.0

92.9

239.0

185.0

-

12

Apigenin

3.27

271.0

153.0

119.0

69.1

+

13

Baicalin

3.36

447.1

271.1

123.1

253.1

+

14

Silymarin

3.32

481.1

301.0

125.1

152.0

-

15

Chrysin

4.14

253.0

143.2

63.1

209.0

-

16

Wogonin

4.22

285.0

270.1

151.2

179.0

+

17

Cannflavin B

4.32

369.1

313.0

298.0

165.0

+

18

Cannflavin A

4.62

437.1

313.1

165.0

298.1

+

19

B-sitosterol

5.47

397.4

161.1

135.1

147.2

+

19 Flavonoids in Solvent

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A method for the extraction of endogenous flavonoids in hemp flower was developed without the need for hydrolysis. 500 mg of ground hemp flower was weighed into a 50 mL centrifuge tube. 10 mL of methanol/water 80/20 was added prior to vortexing (5 seconds) and sonicating (15 minutes). The sample was then centrifuged for 5 minutes at 4200 rpm. The supernatant was diluted 50-fold in 60:40 water:methanol, vortexed briefly, and filtered using a 0.2 μm Thomson SINGLE StEP standard filter vial (cat.#: 25893) prior to analysis.

CBG Hemp Flower

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Peaks

tR (min)

1.

Orientin

1.469

2.

Rutin

1.895

3.

Quercetin-3-D-glycopyranoside

2.010

4.

Luteolin-7-O-glucuronide

2.221

5.

Apigenin-7-O-glucuronide

2.664

6.

Luteolin

2.919

7.

Apigenin

3.266

8.

Cannflavin B

4.321

9.

Cannflavin A

4.620

10.

B-sitosterol

5.472

CBD Hemp Flower

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Peaks

tR (min)

1.

Orientin

1.469

2.

Vitexin

1.827

3.

Rutin

1.895

4.

Quercetin-3-D-glycopyranoside

2.01

5.

Luteolin-7-O-glucuronide

2.221

6.

Apigenin-7-O-glucuronide

2.664

7.

Quercetin

2.753

8.

Luteolin

2.919

9.

Apigenin

3.266

10.

Cannflavin B

4.321

11.

Cannflavin A

4.62

12.

B-sitosterol

5.472

Recovery experiments were performed for CBG and CBD hemp flower by comparing pre-extraction spiked samples against post-extraction spiked samples using two internal standards to aid quantitation, apigenin-d5 and rutin-d5.

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Percent recovery ranged from 83-104% for CBD hemp flower and 83-101% for CBG hemp flower, indicating this is an effective procedure for the extraction of flavonoids from hemp flower. Will flavonoid testing become as routine as cannabinoid testing for the cannabis industry? Is your lab interested or currently running this analysis? Let us know in the comments section below!

  1. Tomko, A. M.; Whynot, E. G.; Ellis, L. D.; Dupre, D. J. Anti-Cancer Potential of Cannabinoids, Terpenes, and Flavonoids Present in Cannabis. Cancers 2020, 12, 1985; doi:10.3390/cancers12071985
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Jamie York, PhD

Jamie York is a scientist in the Applications Lab at Restek Corporation in the LC Solutions department, where she works on the development of novel applications for the food, clinical, and cannabis markets. She earned her PhD in chemistry from The University of Texas at Arlington in 2019. There, she mastered many analytical techniques including gas chromatography–vacuum ultraviolet; gas chromatography–mass spectrometry; matrix-assisted laser desorption/ionization; and liquid chromatography–mass spectrometry with a focus on food and environmental research. Jamie continued her post-doctoral work at The University of Texas at Arlington with a focus on the analysis of mammalian cell culture media by LC-MS/MS.

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