MDEA COA Results: Why Rounding Rules Matter

A certificate of analysis for N-methyldiethanolamine (MDEA, CAS 105-59-9) reports water content as 0.10 wt%, matching the purchase limit. Your quality team asks whether the laboratory compared the limit with the underlying result or its rounded value. Agreeing on that reporting rule before shipment makes the review clearer for both parties.

Separate the measured result from its presentation

A laboratory may retain more digits in its records than it prints on the COA. In a hypothetical example, 0.104 wt% rounds to 0.10 wt% when reported to two decimal places.

The acceptance decision depends on the rule agreed for the specification. ASTM E29 addresses the use of significant digits in test data when determining conformity with specifications. store.astm.org

Define the comparison rule before ordering

Ask the supplier and laboratory how results will be compared with minimum and maximum limits. Record the required reporting precision and applicable rounding convention with the test method.

Where measurement uncertainty forms part of the acceptance procedure, include the agreed decision rule. Eurachem guidance explains how uncertainty information can be used in compliance assessment. www.eurachem.org

Keep calculation precision until the final step

For internal calculations, retain sufficient intermediate digits and round the final reported value according to the agreed procedure. If a result is close to a limit, request the relevant laboratory information before completing the review.

Keep the original report and any clarification together under the same lot reference so receiving staff can follow the final decision.

Include reporting requirements in your MDEA inquiry

Send China Amines Co., Limited your required grade, specification limits, test methods and reporting requirements. Include the net quantity, preferred packaging and destination port so we can review the analytical documentation with the quotation.

Inquiries
info@chinaamines.com

Technical references

• ASTM E29 — Using Significant Digits in Test Data to Determine Conformance with Specifications
• Eurachem/CITAC — Use of Uncertainty Information in Compliance Assessment