Aqueous Dimethylamine: Nitrogen Content vs. Ammonia Nitrogen

China Amines Co., Limited

Dimethylamine contains nitrogen. That fact is useful for a manufacturing material balance, but it does not mean its nitrogen content can be read directly from an ammonia-nitrogen result.

For teams purchasing aqueous dimethylamine, planning downstream production or investigating a process-water stream, three quantities need clear labels: solution mass, DMA mass and nitrogen mass.

The nitrogen atom does not change its identity when the spreadsheet column changes. The quantity being reported certainly can.

1. Calculate the nitrogen contained in DMA

NIST lists dimethylamine’s molecular formula as C₂H₇N and its molecular weight as approximately 45.08. Each molecule contains one nitrogen atom. webbook.nist.gov

Using a rounded nitrogen atomic weight of 14.01, consistent with CIAAW reference values, the approximate nitrogen mass fraction in DMA is:

Nitrogen fraction ≈ 14.01 ÷ 45.08 ≈ 31.1%

For an aqueous solution:

Nitrogen attributable to DMA ≈ solution mass × DMA mass fraction × 0.311

This is a composition-based calculation, rather than a laboratory measurement of a water sample. ciaaw.org

2. Apply the calculation to a defined example

Consider a hypothetical 1,000 kg quantity of solution containing exactly 40.0% DMA by mass.

The calculation excludes nitrogen from any other constituents.

It also does not establish a wastewater discharge quantity. Determining where the nitrogen goes requires a process-specific balance covering products, recovered materials and other relevant streams.

3. Distinguish DMA nitrogen from ammonia nitrogen

Dimethylamine and ammonia are different chemical substances. Reporting nitrogen contained in DMA does not establish the amount present as ammonia or ammonium.

EPA Method 350.1 specifically addresses ammonia-nitrogen determination. Its analytical purpose differs from calculating nitrogen from a dimethylamine feedstock inventory. epa.gov

Consequently, an ammonia-nitrogen result should not automatically be interpreted as the entire nitrogen contribution from DMA-containing material.

The laboratory should assess method suitability and relevant interferences for the actual sample.

4. Understand what TKN includes—and its limitations

EPA Method 351.2 defines total Kjeldahl nitrogen, or TKN, through the ammonia and organic nitrogen converted under its specified digestion conditions.

The method also warns that some nitrogen-containing compounds in industrial wastes, including certain amines, may not be converted adequately. A method name containing “total” therefore does not establish complete recovery of every industrial nitrogen compound. nepis.epa.gov

For DMA-containing matrices, recovery and matrix suitability need supporting laboratory evidence. This limitation does not establish that every DMA sample will fail the method; it establishes why performance should be demonstrated.

5. Match the result to the decision

Before comparing a feedstock calculation with a water-analysis report, confirm:

• Whether the quantity is DMA mass or nitrogen mass.
• Whether the result describes ammonia nitrogen, TKN or total nitrogen.
• Whether units and sample locations are comparable.
• Whether the analytical method is suitable for the matrix.

A nitrogen inventory can support process accounting. An analytical result describes the tested sample under a defined method. Connecting them requires documented assumptions and a clear process boundary.

About China Amines

China Amines Co., Limited welcomes inquiries for aqueous dimethylamine used in chemical manufacturing. Please provide your required concentration, application, quantity, destination and quality-documentation requirements so the proposed supply can be reviewed against your needs.

Visit China Amines for product inquiries.

References

1. NIST Chemistry WebBook — Dimethylamine
2. CIAAW — Standard Atomic Weights
3. US EPA — Method 350.1: Ammonia Nitrogen
4. US EPA — Method 351.2: Total Kjeldahl Nitrogen