How to Read “Not Detected” Results on an MDEA COA

A certificate of analysis for N-methyldiethanolamine (MDEA, CAS 105-59-9) reports an impurity as “ND”. Another reports “<10 ppm.” To assess either result against your purchase specification, ask what reporting threshold was used and whether the method can support the required decision.

Ask what “ND” means on that report

Request the laboratory’s definition of not detected, together with the applicable detection or reporting limit. Eurachem guidance advises care when reporting results as “not detected” because the meaning depends on the analytical method and its capability. Keep the threshold and units with the result during your review. eurachem.org

Distinguish detection from quantification

The limit of detection (LOD) concerns the method’s ability to detect an analyte. The limit of quantification (LOQ) concerns the level at which it can be measured with suitable performance. Ask whether a “less than” figure refers to the LOD, LOQ or another defined reporting limit. Method validation guidance links the required LOQ to the intended analytical working range. eurachem.org

Compare the reporting threshold with your purchase limit

Consider a hypothetical impurity requirement of 20 ppm maximum, with all values expressed on the same mass basis.

Apply the agreed acceptance rule when making the release decision. If the method’s reporting threshold is too high for the requirement, ask the laboratory about a suitable method before arranging further testing.

Include impurity reporting requirements in your inquiry

Send China Amines Co., Limited your required MDEA grade, impurity limits, reporting units and any specified test methods. Include the required reporting capability alongside the net quantity, packaging and destination port so we can review the analytical documentation with the quotation.

Inquiries
info@chinaamines.com

Technical references

• Eurachem — The Fitness for Purpose of Analytical Methods
• Eurachem — Planning and Reporting Method Validation Studies