Four steps to successful substance identification

ECHA has developed a four step approach to successful substance identification. By following these steps and our advice, it will help you to get your substance identification right.


1. Analyse your substance
  1. Firstly, you need to decide whether or not you already have the necessary analytical data to identify your substance for REACH purposes. If you are not the manufacturer, you may request this information from your supplier. If you have the necessary analytical data, you should go to step 1d, otherwise go to step 1b.
  2. Select a representative sample of your substance or several samples from different batches or different time points in the production. If you are an importer of mixtures, you may need to ask your supplier for samples of substances used in the mixture.
  3. Building a correct analytical strategy from the start will save time and money. At this point, you should consider whether you have the necessary functional and knowledge capabilities in-house. If not, you should seek a service provider or laboratory that is familiar with producing analysis for the purpose of REACH. Note that substance identification analysis does not need to be conducted in accordance with Good Laboratory Practice (GLP).
  4. Whichever route you choose, the output should be the same: a set of analytical studies/information that fully identifies your substance. The spectra, chromatograms and other analytical information should be of good quality and fully interpreted.
  5. If there are difficulties in interpretation or technical challenges to conducting analysis, prepare a robust scientific justification and apply alternative techniques. Again expert input may be useful.
  6. The legal text specifies ultra-violet (UV), infra-red (IR) and nuclear magnetic resonance spectroscopy (NMR) or mass spectrometry (MS) to be conducted alongside either high performance liquid chromatography (HPLC) or gas chromatography (GC). For inorganic substances x-ray diffraction (XRD) spectrometry and atomic absorption spectroscopy (AAS) may be necessary alternatives. These techniques require specialist knowledge to perform and interpret their outputs.


2. Detail the composition of your substance
  1. The analysis should now give you a full picture of the composition of your substance.
  2. Analysis of a single sample does not consider the variations based on source (e.g. starting materials) and manufacturing process. These variations are covered by ranges in concentration which can be part of the Certificate of Analysis (CoA) or quality control specification.
  3. For a typical well-defined substance you should have a composition that looks something like this: 


    Name Typical concentration % Concentration range %
    Constituent A 90 85 – 96 
    Constituent (impurity) B 6 4-7
    Constituent (impurity) C 2 0-3
    Constituent (impurity) D 2 0-3


3. Name the substance
  1. Based on the composition you will need to come up with an overall identification – a substance name.
  2. There are different rules depending on the complexity of your substance. They can be found in the ‘Guidance for identification and naming of substances under REACH and CLP'. You may want to ask for expert help on naming your substance if you are unsure.


4. Assign a numerical identifier
  1. Search on ECHA's website using the "Search for Chemicals" tool in Information on Chemicals page to find if an EC or List number already exists for your substance.
  2. It is common but not necessary to connect the chemical name to an inventory number, such as an EINECS or CAS number. Often this number will be present in the safety data sheet (SDS) or certificate of analysis (CoA). You may want to get expert help to identify whether there is an existing inventory number for your substance.

Once you have this information you need to translate it into the electronic format of a IUCLID dossier.

For REACH registration a boundary composition has to be included in the dossier submitted by the lead registrant. The boundary composition reflects the compositions of all members of the joint submission.