Guide · Limits and results
NMT, NLT, LOD, LOQ, ND: reading CoA abbreviations
- Short answer
- NMT means not more than and NLT means not less than; both include the stated limit. LOD is the smallest amount a method can detect, LOQ the smallest it can measure reliably, and ND means not detected. Report means record a value with no limit; Conforms is a statement, not a measurement. LOD can also mean loss on drying.
General background, not regulatory or GMP advice. Your specification and the compendium or standard it cites decide how a limit is read.
Why the same letters cause arguments
A CoA prints limits and results in shorthand, and the shorthand is not fully standardised. NMT and NLT are clear. The trouble starts with abbreviations that belong to the test rather than the limit: LOD in a list of physical tests is usually loss on drying, a percentage of mass lost on heating, while LOD beside a trace-metal result is a limit of detection.
The basics of limit wording are on Certificate of analysis explained, and the rules CertiClean applies are on the specification check page. This guide adds the meaning behind each abbreviation and where it misleads.
Reading an abbreviation you do not recognise
A short routine that works on any certificate.
Look for a legend
Check footnotes, a key or the specification header for the supplier's own definitions. If the document defines the term, that definition governs.
Sort it: limit, result or test name
NMT, NLT, max and min state limits. ND, BLQ and < LOQ are results. LOD, LOI and TAMC can be test names. The role decides how the row is compared.
Find the unit and the basis
A number means little without % or ppm and without as is, dried or anhydrous. See ppm, mg/kg and percent conversions.
For a below-detection result, find the detection value
ND and < LOQ show only that the amount is under what the method can see. Compare that threshold with the limit before accepting the row. Counts have their own conventions: see microbial limits.
For Report and Conforms, note what is missing
Neither gives a number checked against a limit. Decide under your quality system whether the statement or the recorded value is enough.
Record it as printed
Log the abbreviation exactly as the certificate shows it, so a later reader can see what was claimed.
The abbreviations at a glance
How each one reads, and what to watch for.
| Abbreviation | Reads as | Watch for |
|---|---|---|
| NMT, max, ≤ | Not more than; the limit itself passes | Results near the limit: which rounding rule applies |
| NLT, min, ≥ | Not less than; the limit itself passes | The basis: dried or as is |
| < and > in a limit | Strictly below or above; the limit itself fails | < 10 cfu/g rejects a result of 10 |
| LOD (limit of detection) | Smallest amount the method can detect | Not the same as loss on drying |
| LOD (loss on drying) | Percent of mass lost on drying under stated conditions | A test result, not a threshold |
| LOQ | Smallest amount measured with acceptable precision | At or above the LOD for the same method |
| ND | Not detected by the method used | Means little without the detection value |
| BLQ, < LOQ | Below the limit of quantification | May be present but too low to measure |
| Report | Record a value; no acceptance limit | Not a pass |
| Conforms, Complies | The supplier's statement against a requirement | Nothing numeric to verify |
What goes wrong with abbreviations
- Two meanings of LOD. Reading loss on drying as a detection threshold, or the reverse, misreads the whole row. Check the unit: percent of mass for loss on drying, ppm or ppb for a limit of detection.
- ND with no detection value. Not detected by a method that can only see 10 ppm proves nothing against a limit of 1 ppm.
- < LOQ above the limit. A result below 0.01 % cannot show compliance with NMT 0.005 %.
- Conforms next to a numeric limit. It is the supplier's conclusion, not a value you can check.
- Report taken as a pass. A reported value has no limit, so nothing was passed or failed.
- Rounding at the limit. Some pharmacopoeial general notices round a result to the decimals of the limit before comparing, so 0.54 % may conform to NMT 0.5 %. Check the notices that govern your specification, and see out-of-specification results.
How CertiClean helps
CertiClean recognises ≤, ≥, <, >, NMT, NLT, max and min before or after the number, ranges, Negative, Absent, Conforms, Report, ND, BLQ and < LOQ, and decides each row from what is printed. A '<' result passes a maximum only if its value is not above the limit. ND passes a maximum, with a note that no detection value was printed. Complies against a numeric limit is marked could not evaluate. See CoA to Excel and pricing.
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Questions people ask
Do NMT and NLT include the limit?
Yes. A result equal to the limit meets NMT and NLT. A limit written with < or > excludes the value, so 10 cfu/g fails a limit of < 10 cfu/g.
What is the difference between LOD and LOQ?
The limit of detection is the smallest amount a method can detect. The limit of quantification is the smallest amount it can measure with acceptable precision and accuracy. For one method the LOQ is at or above the LOD.
Does LOD mean loss on drying?
Sometimes. In a list of physical tests it usually means loss on drying, reported as a percentage. Next to a trace result it means limit of detection. The unit and the test name usually settle it.
What does ND prove?
Only that the analyte was not detected by that method. To support a limit, the method's detection value needs to be below the limit, so ask for it if it is not printed.
What does Report mean in a specification column?
A value is to be recorded, but no acceptance limit applies. The row cannot pass or fail, so treat it as information for the file.
Is Conforms a test result?
It is a statement. It is common for identification and appearance tests, where there is nothing to measure. Against a numeric limit it gives you no value to verify.
What is the difference between ≤ and < in a limit?
≤ includes the stated value and < excludes it. A result of 10 meets ≤ 10 but not < 10. Check the symbol, not just the number.
What do BLQ and BQL mean?
Both mean below the limit of quantification: the amount may be present but is too low to measure reliably. Compare the printed quantification value with the limit before accepting the row.