Short answer
To test potency in-house you need an HPLC with a UV detector, an analytical balance, certified cannabinoid reference standards, a validated method for each product type, and someone trained to run it. A test consists of weighing a homogenized sample, extracting the cannabinoids into solvent, filtering and diluting, injecting into the HPLC, and quantifying each cannabinoid against a calibration curve. Done properly, results agree with accredited labs.
Why HPLC is the standard for cannabis potency
High-performance liquid chromatography (HPLC) separates each cannabinoid in a sample and measures how much of it is there. Unlike gas chromatography (GC), it works at room temperature, so it measures the acid forms (THCA, CBDA, CBGA) separately from the neutral forms (THC, CBD, CBG). That matters because most of the THC in raw flower is still THCA, and regulators and labels use total THC, which needs both numbers.
Handheld and near-infrared devices can give a rough reading, but they estimate potency from a model rather than measuring each compound. For decisions you will stake a batch on, HPLC is what accredited labs use and what you should compare against.
What you need
- HPLC instrument with UV/Vis detector and a C18 column (the column does the separation).
- Analytical balance for weighing samples accurately, since every result is per gram of sample.
- Certified reference materials (CRMs) for each cannabinoid you report, traceable to NIST. These are what the instrument is calibrated against.
- Validated methods and SOPs for each matrix: flower, concentrates, edibles, tinctures and topicals each need their own sample preparation.
- HPLC-grade solvents, glassware, syringe filters and pipettes.
- Software to identify peaks, calculate results and keep records. A LIMS that produces certificates of analysis saves a lot of manual work.
- Training. You do not need a chemistry degree, but whoever runs the tests needs to follow the SOP exactly.
The CTS-300 ships with all of the above in one package, including the balance, NIST-traceable standards for 15 cannabinoids, validated methods for each matrix, LIMS, and remote training with an application chemist.
How a potency test works, step by step
1. Take a representative sample
Potency varies within a plant and within a batch. Take material from several places (top, middle and lower buds, or several units of a product) and combine it. A perfect analysis of an unrepresentative sample is still the wrong answer.
2. Homogenize
Grind flower to a uniform powder; mix concentrates; for edibles, blend the whole unit so the cannabinoids are evenly spread. Edibles are where poor homogenization most often causes wrong results.
3. Weigh and extract
Weigh a small portion on the analytical balance and add the extraction solvent specified in the method. Shake or sonicate so the cannabinoids dissolve out of the plant material or product.
4. Filter and dilute
Filter out particles and dilute the extract so its concentration falls inside the calibrated range. High-potency concentrates need much more dilution than flower or hemp.
5. Inject and run
The HPLC pumps the sample through the column, where each cannabinoid comes out at its own characteristic time, and the detector records a peak for each one. One injection gives the whole panel.
6. Quantify and report
The software compares each peak with the calibration curve built from the reference standards and converts it to % by weight and mg/g. It then calculates totals:
Total CBD = CBD + (CBDA × 0.877)
The 0.877 factor accounts for the weight lost when the acid form converts to the neutral form on heating. A sample with 23.23% THCA and 0.40% Δ9-THC therefore has about 20.8% total THC.
How to make sure your results are right
- Calibrate with certified standards and re-check calibration on the schedule in your SOP.
- Run a check standard with each batch of samples. If it reads off, stop and fix the cause before trusting the results.
- Test replicates. Two preparations of the same sample should agree closely; if they don't, homogenization is usually the problem.
- Compare with an accredited lab a few times when you start, and occasionally after that, sending a split of the same homogenized sample.
- Keep records: calibration, maintenance and every result, so you can show how a number was produced.
In the NIST Cannabis Laboratory Quality Assurance Program, CTS-300 results on a certified hemp reference material were closer to the NIST certified values than the mean of about 140 participating labs. For the method behind each matrix, see the application notes for flower, extracts and edibles.
In-house testing and compliance
In regulated cannabis and hemp markets, the official compliance test usually has to come from a licensed or registered third-party lab. In-house testing doesn't replace that test. It lets you make decisions before it: when to harvest, whether a formulation is on target, whether a batch is likely to pass. See Checking THC before compliance testing.
Frequently asked questions
Can I test cannabis potency at home or in my facility without a lab?
Yes. With a benchtop HPLC, certified reference standards, validated methods and basic training, a grower, processor or manufacturer can measure potency on site. The official compliance test in regulated markets still has to come from a licensed lab.
How accurate is in-house HPLC testing?
As accurate as the method and calibration behind it. With NIST-traceable standards and a validated method, results match accredited labs; in the NIST hemp study, the CTS-300 was closer to the certified values than the average of about 140 labs.
Do I need a chemist to run an HPLC?
No. Following a validated SOP is a skill most technicians learn in a few training sessions. Interpreting unusual results or troubleshooting is where expert support helps, which is why CTS-300 includes training and ongoing support from application chemists.
What is the difference between THCA and THC on a test report?
THCA is the acid form found in the raw plant; it turns into THC when heated. HPLC measures both separately. Total THC = THC + THCA × 0.877, and that total is what most regulations and labels use.
Can the same instrument test edibles, oils and concentrates?
Yes, with a different sample preparation for each. The CTS-300 includes validated methods for flower, concentrates, edibles, tinctures and topicals.
See what in-house testing would save you
The CTS-300 is a complete benchtop HPLC lab: instrument, balance, reference standards, validated methods, LIMS with COA reports, and training with our application chemist. $18,000, under $5 per test.