GC vs. HPLC for Cannabis Terpene Analysis

: Which is Better?

Gas Chromatography (GC) is generally better for cannabis terpene analysis than High-Performance Liquid Chromatography (HPLC). Here’s why:

GC is faster (~8 minutes vs. 12-20 minutes for HPLC)
GC is more sensitive for volatile terpenes
GC equipment costs less than HPLC
GC is better suited for volatile compounds like terpenes

However, HPLC has advantages for analyzing both terpenes and cannabinoids together.

Quick Comparison:

Factor	GC	HPLC
Speed	Faster (~8 mins)	Slower (12-20 mins)
Sensitivity for volatiles	Higher	Lower
Equipment cost	Lower	Higher
Best for	Volatile terpenes	Non-volatile compounds
Cannabinoid analysis	Total quantity only	Measures acidic forms

Many labs use both methods for comprehensive cannabis analysis. GC is preferred for terpenes, while HPLC excels at cannabinoid profiling. Your choice depends on specific testing needs, budget, and regulatory requirements.

What Are Terpenes?

Terpenes are the smell-good compounds in cannabis (and many other plants). They’re why one strain smells like lemons and another like pine trees. But terpenes aren’t just about nice smells.

Terpene Basics

Terpenes are built from (C5H8)n units. The ‘n’ tells you what kind of terpene it is:

Type	Carbons	Examples
Monoterpenes	10	Limonene, Myrcene
Sesquiterpenes	15	Humulene, Caryophyllene
Diterpenes	20	Phytol

These compounds hang out in the trichomes – those tiny crystals on cannabis buds and leaves.

Why Terpenes Matter

In cannabis, terpenes:

Protect plants from pests
Attract pollinators
Help plants adapt

For humans? They’re part of the "entourage effect" – the idea that terpenes team up with cannabinoids like THC and CBD to boost cannabis effects.

Top Cannabis Terpenes

1. Myrcene

The big kahuna of cannabis terpenes. It can make up 65% of a strain’s terpene profile.

Smells like: Earth and musk
Also in: Mangoes, hops
Might help with: Relaxation, pain

2. Limonene

This one’s all about the citrus.

Smells like: Lemons and oranges
Also in: Citrus peels
Might help with: Mood, stress

3. Caryophyllene

The rebel terpene that can bind to cannabinoid receptors.

Smells like: Pepper and spice
Also in: Black pepper, cloves
Might help with: Inflammation, pain

Terpenes aren’t just a cannabis thing. They’re in lots of plants, which is why some strains might remind you of a forest or a fruit basket.

For the cannabis industry, understanding terpenes is crucial. They shape the user experience and potential health benefits. That’s why precise terpene testing (via GC or HPLC) is a big deal in cannabis analysis.

Gas Chromatography (GC)

GC is the top choice for terpene analysis in cannabis. Here’s why:

How GC Works

GC separates compounds based on volatility:

1. Sample prep: Mix cannabis with solvent (methanol or ethanol) to extract terpenes.

2. Injection: Put extract into GC machine.

3. Separation: Compounds separate in a long column based on vaporization.

4. Detection: FID burns compounds, measures ions to identify and quantify terpenes.

GC Equipment

A typical GC setup includes:

Component	Function
Injector	Puts sample in
Column	Separates compounds
Oven	Controls temperature
FID	Detects compounds
Data system	Shows results

Preparing Samples for GC

Good sample prep is crucial:

Grind cannabis
Mix with solvent
Filter out plant material
Dilute if needed

Watch out: Terpenes evaporate easily. Handle samples with care.

Pros and Cons of GC for Terpenes

Pros	Cons
Quick	Heat can damage some compounds
Great for volatiles	Needs extra steps for acidic cannabinoids
Analyzes terpenes and cannabinoids together	Not great for non-volatiles
Very sensitive	Tricky sample prep

GC is a powerhouse for terpene analysis. Shamanics, a Dutch cannabis testing lab, used GC to measure both THC (18%) and terpenes in one go.

"GC gives fast, accurate profiles of cannabinoids and terpenes with one machine", says the Shamanics team.

For cannabis labs, GC is a solid choice. It’s quick, sensitive, and handles volatile terpenes well. But it’s not perfect. Heat can be tough on some compounds, and you need to be careful with samples to keep those terpenes intact.

High-Performance Liquid Chromatography (HPLC)

HPLC offers a different way to analyze cannabis terpenes than GC. Here’s the scoop:

How HPLC Works

HPLC separates compounds based on how they interact with a column:

Mix cannabis with solvent
Pump mixture through column
Compounds separate
Detector measures compounds

HPLC Equipment

A typical HPLC setup has:

Component	Job
Pump	Moves sample
Injector	Adds sample
Column	Separates compounds
Detector	Identifies compounds
Data system	Processes results

Prepping Samples for HPLC

Good prep is crucial:

Grind cannabis
Extract with solvent
Filter out plant bits
Dilute if needed

Keep non-volatile compounds intact during prep.

HPLC for Terpenes: Pros and Cons

Pros	Cons
Handles non-volatile compounds	Not great for volatile terpenes
High resolution	Takes longer
Separates acidic and neutral cannabinoids	Possible coelution issues
No heat changes	Less sensitive for some terpenes

HPLC is great for complex mixtures, but not always best for terpenes.

"HPLC-UV analysis of terpenes in cannabis is not recommended and may cause more issues than it solves", says a study using a Shimadzu Prominence 20AD HPLC system.

For cannabis labs, HPLC works well for cannabinoids but not terpenes. It’s slower than GC: 12-20 minutes vs. 8 minutes per analysis.

HPLC can separate THC and THCA, which GC can’t. But for terpenes, GC often wins. Many labs use both to get the full picture.

GC vs. HPLC for Terpene Analysis

GC and HPLC each have their strengths for cannabis terpene testing. Let’s compare:

Accuracy and Precision

Metric	GC	HPLC
Terpene Separation	Excellent	Good, but coelution issues
Cannabinoid Separation	Total THC only	Separates THC and THCA
Analysis Time	~8 minutes	12-20 minutes
Volatile Terpenes	Ideal	Not recommended

GC is the star for terpenes, while HPLC shines with cannabinoids. Modern Canna, a Leafly partner in Florida, uses GC-MS to analyze over 40 terpenes accurately.

Sensitivity and Detection Limits

Both methods detect cannabinoids at about 1 ppm. For terpenes:

Aspect	GC	HPLC
Volatile Terpenes	High sensitivity	Lower sensitivity
Non-volatile Compounds	Limited	Better

Modern Canna’s GC-MS breaks compounds into mass fragments, matching them to a database for precise identification.

Cost and Upkeep

Factor	GC	HPLC
Equipment Cost	Lower	Higher
Sample Prep	Simpler	More complex
Maintenance	Less frequent	More frequent

GC is often cheaper and easier to run.

"The traditional method for analyzing terpenes is through gas chromatography with a flame ionization detector (GC-FID)", says a cannabis testing expert.

Shamanics, a Dutch firm, used GC to analyze both potency and terpenes in one test. They found 601.226 µg/L of THC (18% total) and got a full terpene profile.

In short: GC is usually best for terpenes, HPLC for cannabinoids. Many labs use both for a complete cannabis analysis.

Advanced Techniques

Cannabis labs are upping their game with new terpene analysis methods. Let’s check out two that are making waves:

Headspace GC for Volatile Terpenes

Headspace GC is becoming a go-to for volatile terpene analysis. Why? It’s got some serious perks:

Keeps samples intact
Picks up even tiny amounts of terpenes
Cuts down on background noise

Restek Corporation put this method to the test. They used headspace-SPME with GC/MS to analyze terpenes in cannabis and hops. Their setup:

0.2 g dried sample in a 10 mL vial
20-minute extraction
40°C equilibration temp
30-minute equilibration time

The result? They found caryophyllene was the top dog in their cannabis sample.

HPLC with Mass Spectrometry

GC might be the usual suspect for terpene analysis, but HPLC with mass spectrometry (MS) is turning heads. Here’s why:

Feature	What’s Cool About It
No heat needed	Keeps heat-sensitive compounds safe
Tests multiple things at once	Terpenes and cannabinoids in one go
Super precise	Nails down exact amounts of compounds

A game-changing study came up with an LC-APCI-MS/MS method that tackles both terpenes and cannabinoids without any fancy prep. The highlights:

Measures 16 terpenes and 7 cannabinoids in just 25 minutes
Uses simple ethanol extraction
Gets accuracy within 15% for everything it tests
Recovers 80-120% of terpenes

"Our method gives you a quick, all-in-one look at the main stuff in cannabis flowers. It’s even faster than most GC methods", the study authors boasted.

This technique could be a real time-saver for labs looking to streamline their testing.

Rules and Regulations

The cannabis industry’s terpene analysis rules are complex. Here’s the breakdown:

Industry Standards

Cannabis testing rules vary by state:

State	Key Regulations
California	Terpene testing optional (unless labeled), report to 0.01% if tested
Colorado	Allows "fit-for-purpose" methods, including ASTM and AOAC
Maryland	Collaborates with Dept. of Agriculture on pesticide rules
Oregon	ORELAP accredits cannabis testing labs

California’s Bureau of Cannabis Control set clear rules:

Labs must test for cannabinoids, heavy metals, and microbes
Terpene tests optional (unless labeled)
15% leeway on stated cannabinoid levels

Method Validation

Labs must prove their techniques work:

1. Choose a method (GC, HPLC, etc.)

2. Run tests on known samples

3. Check accuracy, precision, and detection limits

4. Document everything

A lab validated a method for both cannabinoids and terpenes:

Used high-speed homogenization for sample prep
Analyzed cannabinoids with HPLC
Tested terpenes with GC-FID
Ran spike recovery tests from 0.03% to 1.5%

Results? Accuracy within 5% and variation under 3%.

"Our method gives a quick, all-in-one look at the main stuff in cannabis flowers. It’s even faster than most GC methods", the study authors noted.

This validation is crucial for lab accreditation. Bodies like A2LA and ANAB offer ISO/IEC 17025 certification.

Rules change fast in this industry. Labs must stay updated with state and federal guidelines.

Picking the Best Method

GC or HPLC for terpene analysis? It’s not a simple choice. Here’s what you need to know:

Key Decision Factors

1. Sample Type

GC shines with volatile compounds. HPLC? It’s better for non-volatile stuff. Cannabis terpenes are volatile, so GC often wins here.

2. Sensitivity Needs

GC is usually more sensitive for volatiles. But HPLC can measure acidic cannabinoids directly – something GC can’t do without extra steps.

3. Budget Considerations

Factor	GC	HPLC
Equipment Cost	Lower	Higher
Per-Analysis Cost	~$0.15	$5-$15
Column Lifespan	Longer	300-500 samples

4. Speed

GC: about 8 minutes. HPLC: 12-20 minutes.

5. Regulatory Requirements

Some states have specific rules. California, for example, allows "fit-for-purpose" methods, including ASTM and AOAC standards.

Using Both Methods

Want the full picture? Use both:

GC: Quick, cheap screening for volatile terpenes
HPLC: Detailed look at cannabinoids and some terpenes

SC Labs uses GC-FID to test up to 39 terpenoids fast.

"Our method gives a quick, all-in-one look at the main stuff in cannabis flowers. It’s even faster than most GC methods", say researchers in a recent study.

Conclusion

GC or HPLC for cannabis terpene analysis? It depends. Here’s a quick comparison:

Factor	GC	HPLC
Volatility	Better for volatile	Better for non-volatile
Speed	Faster (~8 mins)	Slower (12-20 mins)
Cost	Lower	Higher
Sensitivity	Higher for volatiles	Lower for volatiles
Cannabinoid analysis	Total quantity	Measures acidic forms

GC often wins for terpenes: it’s faster, cheaper, and more sensitive to volatiles. Josh Wurzer, President of SC Labs, says:

"Our GC-FID method gives a quick, all-in-one look at the main stuff in cannabis flowers. It’s even faster than most GC methods."

But HPLC has its place, especially for analyzing both terpenes and cannabinoids.

For cannabis businesses:

Know your needs: GC for terpenes, HPLC for full cannabinoid profiles.
Check regulations: Some states have specific rules.
Consider budget: GC is cheaper, but HPLC might be worth it for non-volatiles.
Think speed: GC is faster.
Use both if possible: GC for volatile terpenes, HPLC for cannabinoids and some terpenes.

FAQs

Can you test terpenes in an HPLC?

You can use HPLC for terpene analysis, but it’s not ideal. Here’s why:

Terpenes are volatile, making them better for gas chromatography (GC)
HPLC can cause coelutions with cannabinoids, complicating identification
GC/FID or GC/MS methods work better for terpene analysis in cannabis

BelCosta Labs puts it simply:

"GC/FID or GC/MS is really the most straightforward and recommended way of analyzing terpenes in cannabis."

How many terpenes do most labs test for?

Cannabis has tons of terpenes, but labs focus on a smaller group:

Terpene Count	What It Means
140+	Total terpenes found in cannabis
~17	Common terpenes used for chemotype testing

Why do labs stick to these ~17 terpenes?

They’re the most common in cannabis
They give a good picture of the plant’s chemotype
Testing ALL terpenes would take forever and cost a fortune

Keep in mind: The exact terpenes tested can differ between labs and regions.