How to Read APHA Color on an MDEA Certificate of Analysis

Your receiving team describes a sample of N-methyldiethanolamine (MDEA, CAS 105-59-9) as clear and pale yellow. The certificate of analysis lists an APHA color result. Both observations can describe the same sample. To decide whether the batch meets your purchase specification, check the visual appearance and the measured color against their respective requirements.

Read clarity and color separately

A clear liquid can still have a yellow tint. Clarity describes whether the sample looks transparent or hazy. APHA color expresses color intensity on the platinum-cobalt scale used for clear liquids. A lower reading indicates less color on that scale when results are obtained under comparable test conditions. store.astm.org

Compare the batch result with the agreed limit

Look for the measured result and the maximum allowed value on the COA. For example, if your purchase specification allows up to 50 APHA and the batch result is 35 APHA using the agreed method, the batch meets that color requirement. Assay, water content and other acceptance criteria still need their own checks. Published MDEA technical data sheets can list those items separately. www.amines.com

Confirm the method before comparing suppliers

If one supplier reports “pale yellow” and another reports a numerical APHA value, ask both for a measured result using the method specified in your purchase requirements. If your lab and the supplier report different values for the same lot, confirm the lot identity, test method and sample condition before deciding whether a retest is needed.

Include the color requirement in your MDEA inquiry

When requesting a quotation from China Amines Co., Limited, include the required grade, maximum APHA color, test method if specified, net quantity, packaging and destination port. If your quality team needs the measured color for each lot, request that value on the batch COA.

Inquiries
info@chinaamines.com

Technical references

• ASTM D1209 — Standard Test Method for Color of Clear Liquids (Platinum-Cobalt Scale)
• Amines & Plasticizers Limited — Methyl Diethanolamine Technical Data Sheet