Deep Purple: Identification of origin
of discolouration in CBD products
Brodie Thomson, Dr. Markus Roggen

Introduction
DELIC Labs is a research venture that seeks to add fundamental scientific
insight to the field of cannabis and mushroom production.
We seek to support the cannabis and mushroom industries by
establishing a centralized hub in Vancouver, BC, for collaborative
research focused on:
• Process Design
• Process Optimization
• Process Analytics
• Formulation Research

Collaborative Research
DELIC Labs collaborates with academic, industry and private groups
around the globe. Some highlights of those collaborations are:
• University of British Columbia, Vancouver
• Loyalist College, Belleville
• Via Innovations by Dr. Monica Vialpando
• Veridient Science by Dr. Linda Klumpers
Fundamental Collaboration

Research Topics
• Chemometrics and data analytics for process control and optimization
• Kinetic studies to understand mechanisms
• In-process analytics for process control
• Computational studies to understand mechanisms
• Process development, like crystallization
Fundamental Cannabis and Mushroom Chemistry

3
Outline
- Purple CBD: Current understanding of its origin

3
Outline
- Purple CBD: Current understanding of its origin
- Testing the current hypothesis

3
Outline
- Purple CBD: Current understanding of its origin
- Testing the current hypothesis
- Identification of the compound responsible for the
formation

3
Outline
- Purple CBD: Current understanding of its origin
- Testing the current hypothesis
- Identification of the compound responsible for the
formation
- Future work

CBD Degradation
- Global CBD sales predicted to exceed
US $19 billion by 2025.1
[1] Dobian, CBD Market to reach $19.5 billion by 2025, but only with FDA approval says top researcher. Forbes. July
28, 2021.
Available at https://www.forbes.com/sites/irisdorbian/?sh=2cd295c94bf8.
2

CBD Degradation
- Global CBD sales predicted to exceed
US $19 billion by 2025.1
- Current reports demonstrate differences
between advertised and measured CBD
concentrations.2
(1/3 of tested products contained <50% of
advertised CBD content)
[1] Dobian, CBD Market to reach $19.5 billion by 2025, but only with FDA approval says top researcher. Forbes. July
28, 2021.
Available at https://www.forbes.com/sites/irisdorbian/?sh=2cd295c94bf8.
[2] Liebling, J. P.; Clarkson, N. J.; Gibbs, B. W.; Yates, A. S.; O’Sullivan, S. E. An analysis of over-the-counter
cannabidiol
products in the United Kingdom. Cannabis Cannabinoid Res. 2020. doi: 10.1089/can.2019.0078.
4.5
3.2
0 1 2 3 4 5
Advertised
Measured
Percentage CBD (%)
Mean CBD content in tested
products
Adapted from Liebling et. al2
2

CBD Degradation
- Anecdotal evidence supports the
degradation of CBD solution with multiple
reports of CBD e-liquids and solutions
turning purple.
Sourced from Reddit3
[3] Reddit. CBD E-juice turned purple in the
tankhttps://www.reddit.com/r/Vaping/comments/e0z2ru/cbd_ejuice_turned_purple_in_the_ta
nk/ (Accessed March, 2022). 3

CBD Degradation
- Anecdotal evidence supports the
degradation of CBD solution with multiple
reports of CBD e-liquids and solutions
turning purple.
- Common conception that HU-331 and its
anion are the cause.
[3] Reddit. CBD E-juice turned purple in the
tankhttps://www.reddit.com/r/Vaping/comments/e0z2ru/cbd_ejuice_turned_purple_in_the_ta
nk/ (Accessed March, 2022).
Sourced from Reddit3
3

The Beam Test
- A classical colourimetric test for the identification of hashish using ethanolic KOH (5%).4
[4] Beam, W. Chemistry section in Fourth Report of Wellcome Tropical Research Laboratories, part B.
Khartoum, 1911; pp 25.
4

The Beam Test
- A classical colourimetric test for the identification of hashish using ethanolic KOH (5%).4
Cannabinoids
responsible for a
positive test result5
[4] Beam, W. Chemistry section in Fourth Report of Wellcome Tropical Research Laboratories, part B.
Khartoum, 1911; pp 25.
[5] Adams, R. Marijuana. Harvey Lecture. Bull. N. Y. Acad. Med. 1942, 18 (11), 705-730.
4

The Beam Test
- A classical colourimetric test for the identification of hashish using ethanolic KOH (5%).4
Example quinones
responsible for
the purple
colouration6
Cannabinoids
responsible for a
positive test result5
[4] Beam, W. Chemistry section in Fourth Report of Wellcome Tropical Research Laboratories, part B.
Khartoum, 1911; pp 25.
[5] Adams, R. Marijuana. Harvey Lecture. Bull. N. Y. Acad. Med. 1942, 18 (11), 705-730.
[6] Mechoulam, R.; Ben-Zvi, Z.; Gaoni, Y. Hashish-XIII. On the nature of the beam test. Tetrahedron,
1968, 5615-5624.
4

Tracking HU-331 Concentration
(65% PG, 30% VG, 5%
CBD)
5

Tracking HU-331 Concentration
(65% PG, 30% VG, 5%
CBD)
25 °C, 60% RH, O2
10 weeks
Light + dark storage
10 weeks
Dark storage
25 °C, 60% RH, O2
5

(65% PG, 30% VG, 5%
CBD)
25 °C, 60% RH, O2
10 weeks
Light + dark storage
10 weeks
Dark storage
25 °C, 60% RH, O2
[HU-331]
0.05 µg/g
Tracking HU-331 Concentration
5

(65% PG, 30% VG, 5%
CBD)
25 °C, 60% RH, O2
10 weeks
Light + dark storage
10 weeks
Dark storage
25 °C, 60% RH, O2
[HU-331]
0.05 µg/g
Tracking HU-331 Concentration
[HU-331]
116.03 μg/g
5

(65% PG, 30% VG, 5%
CBD)
25 °C, 60% RH, O2
10 weeks
Light + dark storage
10 weeks
Dark storage
25 °C, 60% RH, O2
[HU-331]
0.05 µg/g
Tracking HU-331 Concentration
[HU-331]
116.03 μg/g
[HU-331]
25.04 μg/g
5

(65% PG, 30% VG, 5%
CBD)
25 °C, 60% RH, O2
10 weeks
Light + dark storage
10 weeks
Dark storage
25 °C, 60% RH, O2
[HU-331]
0.05 µg/g
Tracking HU-331 Concentration
[HU-331]
116.03 μg/g
[HU-331]
25.04 μg/g
- CBD is oxidizing to HU-331
5

(65% PG, 30% VG, 5%
CBD)
25 °C, 60% RH, O2
10 weeks
Light + dark storage
10 weeks
Dark storage
25 °C, 60% RH, O2
[HU-331]
0.05 µg/g
Tracking HU-331 Concentration
[HU-331]
116.03 μg/g
[HU-331]
25.04 μg/g
- CBD is oxidizing to HU-331
- HU-331 is deprotonated
5

Tracking HU-331 Concentration
- CBD is oxidizing to HU-331
- HU-331 is deprotonated
6

Tracking HU-331 Concentration
- CBD is oxidizing to HU-331
- HU-331 is deprotonated
Where is the
base?
6

Tracking HU-331 Concentration
- CBD is oxidizing to HU-331
- HU-331 is deprotonated
Where is the
base?
𝒉𝒗
(65% PG, 30% VG, 5%
CBD)
6

Tracking HU-331 Concentration
- CBD is oxidizing to HU-331
- HU-331 is deprotonated
Where is the
base?
Light-driven deprotonation in neutral, protic media?
𝒉𝒗
(65% PG, 30% VG, 5%
CBD)
6

Tracking HU-331 Concentration
- CBD is oxidizing to HU-331
- HU-331 is deprotonated
Where is the
base?
𝒉𝒗
(65% PG, 30% VG, 5%
CBD)
Mass Chromatogram
6

Isolation of HU-331 and its Anion
7

Isolation of HU-331 and its Anion
Hexane
Water
Hexane
Water
7
Hexane
Water

Isolation of HU-331 and its Anion
Hexane
Water
7

Isolation of CBDHQ and its anion
1H NMR (300 MHz, DMSO-d6) 1H NMR (300 MHz, DMSO-d6)
8

Isolation of CBDHQ and its anion
1H NMR (300 MHz, DMSO-d6) 1H NMR (300 MHz, DMSO-d6)
8

Isolation of CBDHQ and its anion
1H NMR (300 MHz, DMSO-d6) 1H NMR (300 MHz, DMSO-d6)
8

Isolation of CBDHQ and its anion
9

Isolation of CBDHQ and its anion
(2 mg HU-331 in 0.6 mL DMSO-d6)
9

Isolation of CBDHQ and its anion
High absorption coefficient of HU-331 anion
suggests low concentrations can result in drastic
colouration in CBD solutions
(2 mg HU-331 in 0.6 mL DMSO-d6)
9

HU-331 Rate of Decomposition
- Is HU-331 degradation a light-driven process?
10

HU-331 Rate of Decomposition
- Is HU-331 degradation a light-driven process?
HU-331 (0.23 mg) +
dinitrobenzene
internal standard in
DMSO-d6 (0.5 mL)
10

R² = 0.9933
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
0 10 20 30 40 50 60
HU-331
Degradation
Relative
to
T
0
Time (min)
Light
Dark
Storage
Conditions
HU-331 Rate of Decomposition
- Is HU-331 degradation a light-driven process?
HU-331 (0.23 mg) +
dinitrobenzene
internal standard in
DMSO-d6 (0.5 mL)
10

R² = 0.9933
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
0 10 20 30 40 50 60
HU-331
Degradation
Relative
to
T
0
Time (min)
Light
Dark
Storage
Conditions
HU-331 Rate of Decomposition
- 45% reduction in [HU-331] after 60
minutes exposure to white light
- Is HU-331 degradation a light-driven process?
HU-331 (0.23 mg) +
dinitrobenzene
internal standard in
DMSO-d6 (0.5 mL)
10

Conditions Absorption Maximum (λmax)
CBD (30 mg) + HU-331 (1 mg) + Light in IPA (2 mL) 544 nm
CBD (30 mg) + HU-331 (1 mg) + Light in PG (2 mL) 545 nm
Identification of the Anion in CBD Solutions
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
380 430 480 530 580 630 680
Absorbance
(A)
Wavelength (nm)
CBD+HU-331+Light in IPA
CBD+HU-331+Light in PG
11

0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
380 430 480 530 580 630 680
Absorbance
(A)
Wavelength (nm)
Deprotonated HU-331 in IPA
CBD+HU-331+Light in IPA
CBD+HU-331+Light in PG
Conditions Absorption Maximum (λmax)
CBD (30 mg) + HU-331 (1 mg) + Light in IPA (2 mL) 544 nm
CBD (30 mg) + HU-331 (1 mg) + Light in PG (2 mL) 545 nm
HU-331 anion in IPA 542 nm
Identification of the Anion in CBD Solutions
11

0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
380 430 480 530 580 630 680
Absorbance
(A)
Wavelength (nm)
HU-331
HU-331 and CBD at 0.5 mg mL-1 in IPA. Λmax of HU-331, 413 nm.
Role of HU-331 vs CBD
12

0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
380 430 480 530 580 630 680
Absorbance
(A)
Wavelength (nm)
CBD
HU-331
HU-331 and CBD at 0.5 mg mL-1 in IPA. Λmax of HU-331, 413 nm.
Role of HU-331 vs CBD
12

0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
380 430 480 530 580 630 680
Absorbance
(A)
Wavelength (nm)
CBD
HU-331 and CBD at 0.5 mg mL-1
in IPA. Λmax of HU-331, 413 nm.
448 nm light emission
Role of HU-331 vs CBD
13

0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
380 430 480 530 580 630 680
Absorbance
(A)
Wavelength (nm)
CBD
HU-331 and CBD at 0.5 mg mL-1
in IPA. Λmax of HU-331, 413 nm.
448 nm light emission
Role of HU-331 vs CBD
13

0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
380 430 480 530 580 630 680
Absorbance
(A)
Wavelength (nm)
CBD
HU-331 and CBD at 0.5 mg mL-1
in IPA. Λmax of HU-331, 413 nm.
448 nm light emission
Complete degradation of HU-331 in under 15
minutes
Role of HU-331 vs CBD
13

448 nm light emission
Role of HU-331 vs CBD
14

448 nm light emission
48 h
Role of HU-331 vs CBD
14

448 nm light emission
HU-331 responsible for the
colouration
48 h
Role of HU-331 vs CBD
14

448 nm light emission
HU-331 responsible for the
colouration
No HU-331 anion detected by
NMR or mass spectrometry
48 h
Role of HU-331 vs CBD
14

Presence of HU-331 anion?
48 h
15

Presence of HU-331 anion?
48 h
15
No HU-331 anion at high
concentration (>10 mg HU-331)

Conclusions
- HU-331 forms spontaneously within E-
liquids in the presence of oxygen.
- The formation of purple-coloured
CBD solutions is a result of a light-
driven degradation of HU-331.
- HU-331 anion likely not solely
responsible for the purple colour, if at
all.
- Degradation of HU-331 leads to
significant formation of novel products
inside CBD solutions.
16

Conclusions
- HU-331 forms spontaneously within E-
liquids in the presence of oxygen.
- The formation of purple-coloured
CBD solutions is a result of a light-
driven degradation of HU-331.
- HU-331 anion likely not solely
responsible for the purple colour, if at
all.
- Degradation of HU-331 leads to
significant formation of novel products
inside CBD solutions.
48 h
16

Conclusions
- HU-331 forms spontaneously within E-
liquids in the presence of oxygen.
- The formation of purple-coloured
CBD solutions is a result of a light-
driven degradation of HU-331.
- HU-331 anion likely not solely
responsible for the purple colour, if at
all.
- Degradation of HU-331 leads to
significant formation of novel products
inside CBD solutions.
48 h
16

Conclusions
- HU-331 forms spontaneously within E-
liquids in the presence of oxygen.
- The formation of purple-coloured
CBD solutions is a result of a light-
driven degradation of HU-331.
- HU-331 anion likely not solely
responsible for the purple colour, if at
all.
- Degradation of HU-331 leads to
significant formation of novel products
inside CBD solutions.
48 h
16

Future Work
48 h
- What mechanism follows HU-331’s photoexcitation that leads to the purple-coloured
solution?
17

Future Work
- What mechanism follows HU-331’s photoexcitation that leads to the purple-coloured
solution?
- What is causing the purple discolouration if not HU-331’s anion?
48 h
17

Acknowledgements
DELIC Labs:
Kendra Payne
Sajni Shah
Dr Eric Janusson
Dr Tom Dupree
Amanda Assen
Dingding Xuan
Ali Wasti
University of British Columbia:
Dr Glenn Sammis – Supervisor
Dr Tao Huan
Dr Maria Ezhova
18

Thank you! Questions?