Ethylene oxide (ETO) and 2-chloroethanol are tested with a dedicated method, usually gas chromatography with tandem mass spectrometry (GC-MS/MS) or headspace GC-MS. They are not reliably covered by a standard pesticide multi-residue screen, so you must order them separately.
The EU residue definition is the sum of ethylene oxide and 2-chloroethanol, expressed as ethylene oxide. A report that gives only one of the two does not show EU compliance.
Why both compounds are tested
Ethylene oxide is a gas. After fumigation, much of it escapes or reacts. Part of it turns into 2-chloroethanol, which stays in the product much longer. So a lot treated weeks or months ago may show little ETO but clear 2-chloroethanol. Testing both, and adding them up, catches past treatment.
Because ETO use on food is not permitted in the EU, limits are set at the limit of quantification. Even traces can fail. The background is in what ETO treatment is and why EU buyers reject it.
How the lab runs the test
- Sample preparation: the sample is ground and handled cold and in closed containers, because ETO is very volatile.
- Extraction: residues are extracted by a solvent method or released into the headspace of a sealed vial.
- Separation and detection: GC-MS/MS or GC-MS separates and identifies both compounds.
- Calculation: 2-chloroethanol is converted to its ETO equivalent and added to ETO.
- Reporting: each compound, the sum, the LOQ and the method are stated.
What to test and what to ask for
Test sesame, spices and spice powders, and any ingredient used in blends. ETO findings have also affected other products, such as some gums and additives. If you buy several ingredients from the same region, include them in your plan.
- An accredited method for ETO and 2-chloroethanol in your product type.
- LOQs low enough for the EU limit on your product. Ask the lab what its LOQ is for spices or seeds.
- The result for each compound and the sum, expressed as ETO.
- Testing on the final packed lot, after any sterilisation, not on raw material.
Points that cause confusion
Labs differ in method and LOQ, and results near the limit can differ between labs. Agree in advance which lab's result decides, and keep a sealed counter-sample for a retest. 2-chloroethanol can also arise from sources other than ETO fumigation. Where that is argued, the authority's view of the residue definition still applies.
Testing alone is not enough. Write no ETO treatment into the spec, check the processor's sterilisation method at audit, and ask for steam sterilisation where you need a low microbial count. Spice powder buyers can read how to make sure your spice powder is ETO-free.
How we help
We confirm the sterilisation method at the processor and write no ETO treatment into your spec. We send sealed samples from the packed lot for ETO and 2-chloroethanol testing at an NABL-accredited lab. Ask for a free sourcing review.