What to Do When MDEA Assay Results Disagree

The supplier’s certificate of analysis (COA) shows that a batch of N-methyldiethanolamine (MDEA, CAS 105-59-9) meets the minimum assay. Your receiving lab reports a slightly lower result. Before deciding whether to release the lot, check whether the two results came from comparable samples and were measured and reported on the same basis.

Trace both results to the shipment

Match the lot number on the supplier’s COA to the package label and your lab’s sample record. If the shipment contains multiple lots, identify which package was sampled. Ask whether the supplier tested a retained sample from that lot and record where and when your receiving sample was taken. These details help both labs choose the right samples if a retest is needed.

Compare the method, units and reporting basis

Ask both labs for the test method, sample preparation and reporting basis. A published MDEA technical data sheet, for example, specifies gas chromatography for assay. When a report gives GC peak area percent and the purchase specification calls for weight percent, confirm how the assay was calculated before treating the values as equivalent. Check the rounding convention as well, especially if both results are close to the limit. www.amines.com

Agree on how to review a result near the limit

Check the purchase specification for the agreed acceptance rule, including how measurement uncertainty is handled where applicable. If a retest is needed, agree in advance on the sample, laboratory, test method and how the results will be used. If the original tests used different methods, testing portions of the same sample with the agreed method can help narrow down the source of the discrepancy. eurachem.org

Include your assay requirements in the RFQ

When requesting an MDEA quotation from China Amines Co., Limited, include the minimum assay, required test method, reporting basis and batch COA requirements. If your site uses a specific retest or acceptance procedure, share it before ordering so both quality teams can review it against the proposed grade.

Inquiries
info@chinaamines.com

Technical references

• Amines & Plasticizers Limited — Methyl Diethanolamine Technical Data Sheet
• Eurachem/CITAC — Use of Uncertainty Information in Compliance Assessment