Nitrosamine Testing in Cosmetics

Formation starts with your formulation

Diethanolamine (DEA) and triethanolamine (TEA) are in more cosmetic formulations than most manufacturers realise. They appear in shampoos, conditioners, moisturisers, and lotions as emulsifiers, pH adjusters, and foam stabilisers. They are also secondary amines.

When a secondary amine meets a nitrosating agent, the conditions for nitrosamine formation are in place. Nitrosating agents can enter a product through preservatives, through contaminated raw materials, or through nitrite present in process water.

Heat accelerates the reaction. So does low pH, extended storage, and contact with certain packaging materials. A product that passes testing at manufacture may generate nitrosamines over time, particularly if storage conditions vary across the supply chain.

The nitrosamine of most concern in cosmetics is N-nitrosodiethanolamine, known as NDELA. It forms directly from DEA under nitrosating conditions and is classified as a probable human carcinogen. EU regulators have issued product safety alerts for NDELA concentrations ranging from 52 μg/kg to over 56,000 μg/kg in cosmetic products, a wide range that reflects how unpredictable formation can be.

NDELA is not the only nitrosamine of concern. Any secondary amine in a formulation is a potential precursor. The challenge is that you may not know which nitrosamines are present, or whether they are forming over time, without a method capable of detecting all of them.

The 50 μg/kg limit and what it means for you

EU Cosmetics Regulation EC 1223/2009 sets a limit of 50 μg/kg for total nitrosamines in cosmetic products. Products containing nitrosamines above trace levels that are technically unavoidable under good manufacturing practice are considered non-compliant. The same limit applies to products placed on the UK market under equivalent domestic legislation.

The regulation does not mandate a single analytical method. It sets the limit, and the responsibility to demonstrate compliance rests with the manufacturer or responsible person through a validated testing approach.

The May 2026 CMR amendments are not the end of this. The EU has been tightening cosmetic ingredient restrictions consistently for three years. Nitrosamines are on the list and they are staying there.

Testing for nitrosamines

Total Analysis: ATNC

ATNC, or Apparent Total Nitrosamine Content, is the recognised analytical method for demonstrating compliance with the 50 μg/kg limit under EC 1223/2009. It measures the combined nitrosamine content of a sample through a controlled chemical reaction that releases the N=O group common to all nitrosamines, then detects the resulting nitric oxide using a thermal energy analyser. The output is a single value for total nitrosamine content.

This approach does not identify which nitrosamines are present. It confirms if the total amount falls above or below the 50 μg/kg limit. For routine compliance testing and incoming raw material screening, it is the fastest way to establish if nitrosamine activity is present at all. A sample that falls below the limit cannot contain any individual nitrosamine above it.

Our webinar Detecting Unexpected Nitrosamine goes into more detail. You can watch it on demand here.

Targeted analysis: GC-TEA

When a sample shows elevated total nitrosamine content, or when individual nitrosamine identification is required, gas chromatography coupled with a thermal energy analyser provides compound-specific results. The GC separates individual nitrosamines as they travel through the column. The TEA responds specifically to the N-O bond, producing distinct peaks for each compound present.

The TEA's specificity is an advantage in complex cosmetic matrices. Many co-eluting compounds produce no TEA signal, which means cleaner chromatograms and more reliable quantification. The detector responds to nitrosamines it has not been specifically calibrated for, so unexpected compounds appear as distinct peaks rather than going undetected.

For most cosmetics manufacturers, ATNC analysis covers routine compliance testing. GC-TEA is used when speciated data is needed: during investigation, formulation review, or when regulators request compound-specific confirmation.