What ND and Below LOQ Mean on a Fatty Amine COA
2026-11-10
What ND and Below LOQ Mean on a Fatty Amine COA
A receiving lab reviewing C12–14 alkyldimethylamine sees “ND” next to an impurity on the certificate of analysis. The purchase specification sets a numerical maximum. Before the lab can use the result for acceptance, it needs one more piece of information: the threshold behind “ND.” limit of detection (L03540)
Detection and quantification answer different questions
| COA entry | What to check |
|---|---|
| ND — Not detected | Ask which threshold the lab uses for this entry and request its numerical value and unit. |
| <LOQ — Below the limit of quantification | The result is below the level at which the method can provide a quantity that meets its stated performance criteria. A signal may still have been detected. |
| <0.05 wt% | The threshold is visible. Confirm what kind of limit it represents and which method produced the result. |
The limit of detection describes how low a level the method can detect with reasonable certainty. The limit of quantification describes how low a level the method can quantify to the required standard. Both depend on the analytical procedure. limit of detection (L03540)
Compare the reporting threshold with the purchase limit
Suppose the agreed maximum for a specified impurity is 0.10 wt%. A result of <0.05 wt% can support acceptance if it comes from the agreed method and meets the buyer’s decision rule. A result of <0.20 wt% leaves the decision open because the threshold is above the purchase limit. These values illustrate the comparison. dev.eurachem.org
For a plant qualifying C12–14 alkyldimethylamine as a tertiary amine intermediate, agree on the impurity, unit, test method, and reporting threshold before the trial shipment. When contacting China Amines Co., Limited, share those requirements and request a representative COA so your quality team can confirm the proposed reporting format.
Technical references
- IUPAC Gold Book — Limit of detection
- IUPAC Gold Book — Limit of quantification
- Eurachem — Use of uncertainty information in compliance assessment