Non-Detectable THC: LOQ vs LOD

Seeing “non-detectable THC” on a Certificate of Analysis (COA) can be reassuring, but what does it actually mean? The answer usually depends on two lab metrics: the Limit of Detection (LOD) and the Limit of Quantitation (LOQ). Understanding LOQ vs LOD for THC helps you read COAs accurately, set expectations for “THC-free,” and make informed choices.

This page focuses on the analytical testing side of THC-free. For foundations on terms and product types, see Basics of THC-Free CBD, What Is THC-Free CBD?, and Broad Spectrum vs Isolate (THC-Free Explained). We link to these topics rather than covering them in depth here.

What does “non-detectable THC” mean?

“Non-detectable THC” (sometimes written as ND) typically means the lab did not observe a signal for THC above its detection threshold. Depending on the lab, ND can indicate either:

Below LOD: No detectable signal above noise.
Below LOQ: A signal may be detectable, but it’s not precise enough to report a numeric value.

On COAs, you might see ND, BDL (below detection limit), BLQ/BLOQ (below LOQ), “<LOQ,” or “0.00%.” These do not always mean absolute zero THC; they reflect the method’s sensitivity.

LOQ vs LOD for THC: definitions and why they matter

Limit of Detection (LOD)

LOD is the lowest THC level the method can detect as present, typically established by a signal-to-noise ratio around 3:1 or similar statistical criteria. Values below LOD are indistinguishable from background noise.

Limit of Quantitation (LOQ)

LOQ is the lowest level the method can measure with acceptable accuracy and precision, often tied to a signal-to-noise ratio near 10:1. If a result is between LOD and LOQ, the lab may report “detected, <LOQ” rather than a number. This is the practical “limit of quantitation THC” that controls whether a numerical value appears on your COA.

Practical example

Imagine a lab with LOD = 0.002% and LOQ = 0.010% THC by weight. If a product contains 0.006% THC, the lab may report “Detected, <LOQ” or simply “<LOQ/ND.” If it contains 0.012%, it can be quantified and reported numerically.

How labs determine LOD/LOQ for THC

Accredited labs validate methods using calibration curves, blanks, and replicate analyses. Common instruments for cannabinoids include HPLC-UV/DAD and LC-MS/MS; GC methods may require derivatization because THC can convert at high temperatures. LOD/LOQ vary by method, instrument, matrix (oil, gummy, topical, flower), and sample preparation. Lower LOD/LOQ values indicate higher sensitivity.

Reading a COA: where to find LOD/LOQ and units

Look for a “Method” or “Reporting Limits” section listing LOD and LOQ for Δ9-THC and THCA.
Check units: % (w/w), mg/g, mg/mL, or mg/serving. Results depend on the basis used.
Total THC may be reported as Δ9-THC + (THCA × 0.877). Know which value your label cites.
Match the COA lot/batch ID and product name to the item in hand.
Note any measurement uncertainty and rounding rules (e.g., two decimals can show “0.00%” even when trace amounts may be present below LOQ).

LOQ vs LOD THC and “THC-free” labeling

In practice, “THC-free” on a label usually means Δ9-THC is non-detectable at the lab’s LOQ. Because LOQs differ between labs and methods, one product tested at LOQ 0.01% may report ND while another tested at LOQ 0.002% might still show a tiny numeric value. When comparing products, look for a clearly stated, low LOQ and consistent ND results across batches.

Drug testing awareness

Even when a COA shows ND for THC, there is no guarantee of passing a drug test. Trace levels below LOQ, cross-contamination, serving size, frequency of use, and individual metabolism can all influence outcomes. If avoiding THC exposure is critical, consider products with very low LOQ, verified ND batch COAs, and discuss concerns with your employer or a qualified professional. This is general information, not legal advice.

Practical checklist when comparing products

LOQ clarity: Is LOQ for Δ9-THC explicitly listed? Lower is better for “ND” confidence.
Method transparency: Instrument and method (e.g., HPLC) are documented.
Units and basis: % vs mg/g vs mg/serving are specified.
Batch matching: The COA lot number matches your product.
Accreditation: Look for ISO/IEC 17025 or similar lab credentials.
Consistency: ND across multiple batches and time points.

Common reporting nuances

ND/BDL: Below the method’s detection limit. No reliable detection.
BLQ/BLOQ or “<LOQ”: Detected but too low to quantify accurately.
Rounded zeros: “0.00%” may reflect rounding when the true value is below LOQ.
Total THC: Δ9-THC + (THCA × 0.877). Hemp regulatory limits often reference total THC; confirm the basis on the COA. This is not legal advice.

FAQ

Is “non-detectable THC” the same as zero?

No. ND means THC is below the method’s detection or quantitation limits. It does not prove absolute zero.

What LOQ is “good enough” for THC-free?

There’s no universal standard, but many brands aim for LOQs at or below 0.01% for Δ9-THC. Lower LOQs increase confidence in ND results.

If THC is ND, can a serving still contain some THC?

Yes. Example: If LOQ is 0.01% w/w and a gummy weighs 4 g, the maximum unquantified THC could be less than 0.4 mg per gummy (0.0001 × 4000 mg). Actual content may be lower.

Are LOQ and LOD the same across labs?

No. They vary by lab, instrument, matrix, and validation. Always read the COA for the specific product and batch.

Disclaimer

This content is for general informational purposes only and is not medical, legal, or testing advice. Consult qualified professionals about your situation, especially regarding drug testing or regulatory compliance.

Explore carefully vetted THC-free options: Shop THC-free products.

Summary

“Non-detectable THC” depends on a lab’s LOD and LOQ. LOD signals whether THC can be detected at all; LOQ governs whether a precise number can be reported. ND or “<LOQ” does not guarantee absolute zero or drug test outcomes. For greater confidence, look for low LOQs, transparent COAs, accredited labs, and consistent batch results—and use this information alongside professional guidance.