A Better Understanding of Cannabis 

Chemistry to Aid in Vapor Phase 

Detection of Intoxication

Tara Lovestead, Ph.D.

Material Measurement Laboratory at NIST

Applied Chemicals and Materials Division, Boulder, CO
Collaborators

• Applied Chemicals and Materials Division

− Tom Bruno 

• Chemical Sciences Division 

− William MacCrehan

− Mimy Young

− D’Nisha Hamblin

− Bruce Benner

− Michele Schantz •

• Florida International University

− José Almirall

− Sigalit Gura

2
Cannabis/Marijuana Decriminalization 

• Medical marijuana – 22 states and 

Washington D.C.

• Recreational marijuana

– Legal in Colorado, Washington, Alaska 

and Oregon

– Voting today! CA, AZ, NV, MA and ME

• Feb 2014 - Congress enabled 

financial institutions to do business 

with legal sellers

3

Ø Made imperative the need to detect cannabis-induced 

intoxication for both law enforcement and workplace safety.
The Endocannabinoid System

• Cannabinoid receptor types (CB):

• CB1 – nerve cells in brain, spinal cord, eyes

• CB2 – immune system, spleen, peripheral 

nerves

• Endocannabinoid neurotransmitters

• Regulate fear, stress, memory, pain, 

inflammation, appetite, immune 

function, depression

• Phytocannabinoids

• Synthetic cannabinoids

4
Synthetic Cannabinoids

• Sprayed onto plant material, 

paper 

• Sold as “potpourri” or “herbal 

incense”

• Innervate with the 

cannabinoid receptors

– More potent than endo- or 

phytocannabinoids

– Tremors and seizures, 

hallucinations, delusions, and 

violent behavior

• Active ingredients in 

constant flux

5

Poisons yield unpredictable results by Ben Wallace, theadvocate.com/csp/mediapool/sites/Advocate/assets/templates...

Spice

K2

Bliss

Fake Weed 

Yucatan Fire 

Skunk

Moon Rocks

Genie

Scooby Snacks
Cannabis Chemistry

• Made up of over 400 compounds

• 100+ phytocannabinoids

– cannabidiol (CBD)

– Δ9-tetrahydrocannabinol (Δ9-THC)

• Main psychoactive cannabinoid

• Responsible for “high” feeling

– Effects pain sensation, mood 

(euphoria/paranoia), memory, 

appetite, coordination

– Innervate with CB1 and CB2

• Terpenes - aroma

• Challenge - Schedule I drug

6

Terpenes
Physiological Complexities

• D9-THC levels spike within 

minutes, drop rapidly

• Body mass index

• Detect 1-2 ng/ml THC in 

the blood 

– Chronic user – 2 days

– Occasional user – 8 hours

• D9-THC detected depends 

on how consumed

– Smoking, eating, tinctures, 

teas, vaporization, patch

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Detecting D9-

THC

• Readily detect in blood, urine, hair, 

sweat, oral fluid (saliva), breath

• D9-THC in blood

– Per se limits: CO limit, 5 ng/mL 

– “zero tolerance” laws

• Does not correspond to intoxication

Ø Other chemical markers indicative 

of intoxication?

– Synthetic cannabinoids

8

Shutterstock, http://www.macleans.ca/society/health/researchersdiscover-a-blood-test-for-suicide-risk/

http://www.carsguide.com.au/car-news/increase-in-p-platedrug-drivers-31424
Breath Tests for D9-THC

• Advantages

– Non-invasive

– Portable

– Indicate recent use (0.5 – 2 hours) 

• Challenges

– Impairment may last longer than 2 

hours

– Passive exposure?

– Does it determine degree of 

intoxication?

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SensAbuesTM filter holder

http://marijuanastock

s.com/marijuanabreathalyzer-makessignificantbreakthrough/

M. A. Huestis et al, “Cannabinoids in exhaled breath following controlled administration of smoked cannabis,” Clinical Chemistry 59:12, 1780-1789, 2013.
Our Approach

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• Artificial breath

• Determine the chemical 

signature of intoxication

• Develop data analytics

• Vapor pressures

• Molecular interactions

• Partition coefficients

• Material selection for adsorption

• Develop desorption techniques

• Begin with pure compounds and 

breath surrogates

Fundamental Data

Materials Development

“Breathalomics”
Fundamental Data: Vapor Pressure

• Volatile substance - evaporates or sublimes 

readily at normal temperatures and pressures

– Evaporation: liquid phase to gas phase

– Sublimation: solid phase to gas phase

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Characterization of Δ9-THC & CBD

• Large molecules with low 

vapor pressures

• Reactive with oxygen, heat, 

light

• Unstable for long 

measurement times

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Accurate measurements are especially 

challenging for mixtures!

http://foyfarmacy.com/3x-isolate-what-does-that-mean/
Porous Layer Open Tubular (PLOT)-

Cryoadsorption

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Robust,	reusable,	cheap,	large	temperature	operability	(less	volatile	

solutes),	and	sorbent	phases	can	be	tailored	for	application	

Sorbent is porous 

throughout

0.1 to 3 meter long

A dynamic HS sampling technique

alumina

polymeric

clay
PLOT – Cryoadsorption (PLOT-Cryo)

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COLD!

Tcryostat = - 20 oC

Toven = 60, 80, 100, 120 & 140 °C 

Sweep Gas

Bruno, T.J., “Simple, quantitative headspace analysis by cryoadsorption on short alumina PLOT columns,” J. Chromatogr. Sci., 47, 5069-5074, 2009. 
Gas Chromatography – Mass 

Spectrometry

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0

1

2

3

4

5

6

7

8

2.3 2.5 2.7 2.9 3.1

ln( g / L x 10

7 ) 

1000/T, K-1

Quantitative, Sensitive Recovery of Δ9-

THC

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A linear relationship provides enthalpy of interaction

ΔH = 91.0 kJ/mol

Toven = 140, 120, 100, 80, 60 °C 

1

10

100

1000

10000

100000

40 60 80 100 120 140 160

Psat *10

5 / Pa

Collection Temperature / °C

Vapor Pressure (Pa x 105) for both 

Δ9-THC and CBD

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Breath Collection: PLOT – Cryo

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Fundamental thermophysical properties data and adaptable 

technology for in-the-field sampling and pre-concentration.

A single PLOT capillary embedded 

in an epoxy wafer.

Tom Bruno demonstrating the hand 

piece and portable PLOT-Cryo.

T.J. Bruno, “Field portable low temperature PLOT-Cryo headspace sampling and analysis part 1: Instrumentation,” J. of Chrom. A, 1429, 65-71, 2016.
Breath Collection: Capillary 

Microextraction of Volatiles (CMV)

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CMV Device Specifications

• 2 cm long open ended glass 

capillary tube 

• Seven 2-mm wide by 2-cm long 

sorbent (PDMS) coated glass fiber 

strips 

• Surface area 5000 times greater 

than SPME fiber

• Sampling time as low as 30 s

• Vacuum pump suction is 1L/min

CMV

CMV Device

• High sensitivity

• Low sampling time

• Ability for on-site sampling of 

VOC compounds

Wiebelhaus, N., et. al., “Differentiation of marijuana headspace volatiles from other plants and hemp products using CMV coupled to GC-MS,” Forensic Chemistry 2, pg 1-8, 2016.

Use CMV device for breath collection of cannabis-related metabolites.
Thermal Desorption: CMV

Gas

Detector

Oven

GC Flow 

Outlet

Thermal Probe

CMV

Liner

GC 

Injector

Probe 

adapter

Column 

Oven

Data Recorder

Probe 

Flow inlet

0.0E+00

1.0E+06

2.0E+06

3.0E+06

4.0E+06

5.0E+06

6.0E+06

7.0E+06

8.0E+06

9.0E+06

415056636976828894

100106112118124129135142148155161168175

Abundance

m/z

84

133

162

92 119 65 51

42

105

Thermal Separation Probe 

(TSP)

GC/MS

TD-CMV-GC/MS

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“Breathalomics” - Artificial Breath 

Generator Breakthrough 

0

10

20

30

40

50

60

70

80

90

100

2,5-DMF Tetradecane Caryophyllene

%	Breakthrough	on	2nd	CMV

*calculations	based	on	SIM	AUC	(n=3)

500	ml/min 400	ml/min 300	ml/min 200/ml/min

Gas Inlet

Dynacalibrator Model 150

37.0°C

Chamber Temp

Permeation

Tubes

Chamber

Vapor Outlet

Tubing

CMV 1

CMV 2

Permeation Tube Vapor Generator

CMV Breakthrough Experiment

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Summary

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• Artificial breath

• Determine the chemical 

signature of intoxication

• Develop data analytics

• Vapor pressures

• Molecular interactions

• Partition coefficients

• Material selection for adsorption

• Develop desorption techniques

• Begin with pure compounds and 

breath surrogates

Fundamental Data

Materials Development

“Breathalomics”
Thank you!

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Funding – Special Programs Office