UK REACH and Your Supply Chain

UK REACH and Your Supply Chain

Up until Dec 31st, 2020, there was one piece of chemical legislation that governed the UK and Europe. There are now two pieces of legislation. Under the Northern Ireland Protocol, the EU REACH Regulation continues to apply to Northern Ireland, while UK REACH provides the regulatory framework for chemicals in Great Britain. These two pieces of legislation are built around the same principles however they are separate. Though UK REACH aims to replicate EU REACH in principle as closely as possible, the legislative split between EU and UK REACH now means that all companies wanting to place their products on the markets in the EU and UK will have to reassess their supply chains and their activities in order to identify changes in their compliance obligations. UK manufacturers and importers will have obligations under UK REACH. Existing EU REACH registrations submitted by UK legal entities should have been Grandfathered to UK REACH by 30th April 2021, but these will only cover the UK market.

UK REACH includes provisions that allow existing UK downstream users previously benefiting from EU REACH registrations held by EU legal entities, and UK importers benefiting from existing EU REACH registrations held by an EU Only Representative, to continue to benefit from those registrations for a limited period of time, if they submit Downstream User Import Notifications by October 2021 to the UK authorities.

If a UK legal entity wants to place a new substance on the market in the UK they will have to complete a UK registration via the Inquiry dossier route, analogous to the EU REACH registration process. UK companies do not have to comply with EU REACH. They can still sell to EU companies who are registered as EU REACH importers. If UK companies (manufacturers and formulators) want access to the entire EU market they can employ an EU Only Representative to act on their behalf and register the substances, they ship to the EU. In this scenario, their EU customers would be Downstream Users under EU REACH.

It is important for EU companies to be aware of their existing supply chains and understand how the separation of UK REACH and EU REACH will affect them as they lose access to the UK market. EU REACH registrations previously submitted by legal entities outside the UK are not valid in the UK and will no longer cover the UK importers. Non-UK suppliers should consider the need to nominate a UK Only Representative (OR) to act on their behalf and register the substances they ship to the UK. This would give them access to the entire UK market.

The principles of registration in UK REACH are the same as EU REACH in that a registration is a substance per legal entity. The registration process is analogous to EU REACH and the UK HSE webpage directs users to the EU ECHA guidance documents for dossier preparation.

The first step of any new registration is to submit an Article 26 Inquiry dossier. The purpose of the Inquiry dossier is to establish the substance identity and the information requirements for this under UK REACH are the same as for EU REACH as described by the UK HSE and summarized in the box below.

Information requirements for an Inquiry dossier:

1.  Identity of the requested submitter (Comply with UK REACH account)

2. Identity and composition of substance (IUCLID Section 1.1 Identification, 1.2 Composition)

3. Analytical data (IUCLID Section 1.4 Analytical Information)

4. Information requirements (IUCLID Section 14 Information requirements)

Substance identity is central to UK REACH compliance. All registrants of the same substance must work together to submit a joint dossier. Each member of the joint registration must submit their own data in their co-registrant dossier which includes analytical data to unambiguously confirm substance identity. For new substance registrations, or new product and process orientated research and development (PPORD) notifications, chemical property data, generated to meet regulatory requirements is a mandatory part of the UK REACH Registration process. This data should be submitted in the form of a technical dossier.

Substance Identity - Definitions

There are some important definitions that are relevant to substance identity and these include the difference between a substance and a mixture

A Substance means a chemical element and its compounds in the natural state or obtained by any manufacturing process, including any additive necessary to preserve its stability and any impurity deriving from the process used, but excluding any solvent which may be separated without affecting the stability of the substance or changing its composition.

A Mixture means a mixture or solution composed of two or more substances.

The registration is always at the substance level. Any mixtures containing substances manufactured or imported above 1 tonne per year require registration of the substances.

Well-defined substances can be further characterized as either a mono-constituent substance or a multi-constituent substance:

 A mono-constituent substance means a substance in which one constituent is present at a concentration of at least 80% and which contains up to 20% (w/w) of impurities. There is an expectation, for substance identity purposes, that one would identify and quantify, constituents present at levels equal to or above 1%.

A multi-constituent substance means a substance consisting of several main constituents present at concentrations generally ≥ 10% and < 80% (w/w). These substances are typically named as “Reaction mass of [names of the main constituents]”. Again, there is an expectation for substance identity purposes to identify and quantify constituents present at levels equal to or above 1%.

A third category is Substances of Unknown or Variable composition, Complex reaction products, or Biological materials (UVCB). These are substances that are so complex they cannot be sufficiently identified by their chemical composition perhaps due to the number of constituents being relatively large and/or the composition is, to a significant part, unknown and/or the variability of composition is relatively large or poorly predictable. For these substances there are no impurities, instead, all are considered to be part of the substance. Due to their complexity, the substance identity for these substances includes the starting materials and the manufacturing process. The expectation is to identify all constituents greater or equal to 10%.

Substance identity information requirements

In reference to EU Regulation (EC) 1907/2006 Annex VI, Section 2, for each substance the information required should be sufficient to enable each substance to be identified. If this is not technically possible or it does not appear scientifically necessary to give information on one or more of the items below the reasons should be clearly stated in the inquiry dossier. These items include the name or other identifier of each substance, information related to the molecular and structural formula of each substance, and the composition of each substance as per the following structure:

2.1. Name or another identifier of each substance

2.1.1. Name(s) in the IUPAC nomenclature or other international chemical name(s)

2.1.2. Other names (usual name, trade name, abbreviation)

2.1.3. EINECS or ELINCs number (if available and appropriate)

2.1.4. CAS name and CAS number (if available)

2.1.5. Other identity code (if available)

Information is then required covering the molecular and structural formula of each substance including optical activity and typical ratio of stereoisomers if that is relevant to the substance in question:

2.2. Information related to the molecular and structural formula of each substance.

2.2.1. Molecular and structural formula (including SMILES notation, if available)

2.2.2. Information on optical activity and typical ratio of (stereo) isomers (if applicable and appropriate)

2.2.3. Molecular weight or molecular weight range


The compositional information regarding each substance must include a description of the degree of purity. This is based on the concentration of the main constituents: their typical concentrations along with upper and lower limits. Particular attention to the nature of impurities is recommended. This includes describing and quantifying the main impurities present (%) including isomers and also by-products or additives. Additives are substances that have been intentionally added to stabilize the substance – they contribute to the substance composition (but not to the naming) and include stabilizing agents or inhibitors.

2.3. Composition of each substance

2.3.1. Degree of purity (%)

2.3.2. Nature of impurities, including isomers and by-products

2.3.3. Percentage of (significant) main impurities

2.3.4. Nature and order of magnitude (… ppm, … %) of any additives


Chemical data requirements

Annex VI, Section 2 also describes analytical data requirements including spectral data and chromatography data and requirements for analytical method description. Spectral data provides information about the structure of the substance. Liquid or gas chromatography methods are used to provide information about the purity of the substance being registered.

2.3.5. Spectral data (ultra-violet [UV], infra-red [IR], nuclear magnetic resonance [NMR] or mass spectrum [MS])

2.3.6. High-pressure liquid chromatogram [HPLC], gas chromatogram [GC]

2.3.7. Description of the analytical methods or the appropriate bibliographical references for the identification of the substance and, where appropriate, for the identification of impurities and additives. This information shall be sufficient to allow the methods to be reproduced.


The analytical reports need to include a detailed description of the sample preparation and methods used which constitutes enough information to allow the methods to be reproduced and the data to be evaluated. If you are not submitting analytical reports for any of the methods listed in sections 2.3.5 and 2.3.6 above, it is advisable to explain your rationale. The justification should be based on technical feasibility or scientific necessity, meaning robust scientific argumentation. This helps with dossier evaluation

REACH Inquiry dossier requirements

The REACH Inquiry dossier requirements include sections on identity, composition, and analytical data. The section on composition includes the constituents/impurities/additives with each entered individually with typical % and range: min/max%. The section on analytical data is needed to verify the composition of your substance and to ensure that the chemical identifiers, such as IUPAC name or CAS number, are appropriate. Analytical reports are uploaded for review by the Agency. For each report, there is a requirement to indicate purpose and data type.

Section 1.1 Identity - Name, CAS, EC. Use of reference substances

Section 1.2 Composition -

Section 1.4 Analytical data

Section 14 Information requirements


A multi-technique approach to substance identity testing

A multi-technique approach is used for substance identity testing because different analytical techniques provide information on different aspects of a substance's structure and purity. Spectral data can provide information on structure and chromatography can provide information on purity, however, with mass spectrometry detection coupled to these chromatography approaches, these methods can also provide identity data. For dossier preparation purposes, the analytical data is submitted per individual technique. With this in mind, it is useful to include a summary that explains how the analytical data relates to the composition declared. It is also very important when considering analytical data that the results obtained by each analytical technique need to be interpreted within the limits of the technique.

Infrared spectroscopy

Infrared spectroscopy provides information about the functional groups present. As functional groups can be present in many different substances, information from infrared spectroscopy cannot be considered definitive data pertaining to identity but it is useful to check that the functional group information in the spectrum supports that expected from the molecular formula. In figure 3 we see an infrared spectrum of Bis(hydroxyethyl) terephthalate. If the substance gives rise to a complex infrared spectrum indicating the presence of many different functional groups, the spectral information can then be used as a “chemical fingerprint” and compared against structural data from similar complex samples.

Nuclear Magnetic Resonance (NMR)

Nuclear Magnetic Resonance (NMR) is a key technique for substance identity. It provides information on how neighboring atoms of certain nuclei in a molecule are connected together, as well as how many atoms of these types are present in different locations in the molecule. Primarily 1H, 13C NMR spectroscopy techniques are used however other nuclei can be used for example phosphorus 31P if relevant to the substance. NMR can also potentially be used in a quantitative manner. In figure 4 we see an NMR spectrum for Bis(hydroxyethyl) terephthalate.

Mass spectrometry (MS)

Mass spectrometry, particularly electron ionization approaches gives valuable data on substance identified as the fragmentation pattern may be related to the structure and can be compared with a reference database. Softer ionization approaches such as electrospray ionization (ESI) can provide mass data on the molecular ion. For interpretation of this data, you would need to know the context for example the starting materials, the reaction pathway expected substance identity and can we relate the molecular ion data to the information we have.

Chromatography Data Examples

Gas Chromatography

Gas chromatography separates the constituents within a substance. The column, temperature, carrier gas, and detector settings can all be varied in relation to the type of sample under analysis. In figure 6A we can see a single peak in the chromatograph which indicates a monoconstituent substance. Purity information can be determined from the number of peaks and the % composition from peak area normalization.

High-performance liquid chromatography

Liquid chromatography allows the separation of the constituents within a substance. The columns and solvents used in the liquid phase can be varied in relation to the type of sample under analysis. Typically, UV detectors are used, although there is a range of different detectors that can be used including mass spectrometry. Purity information can be determined from the number of peaks the percentage peak area and retention times.

Examples of additional useful analytical techniques

For some substances, information from the spectral methods and chromatography approaches mentioned above is not sufficient or appropriate and, in such cases, you need to provide other types of identification data. For example, in the case of inorganic substances, X-ray diffraction (XRD), X-ray fluorescence (XRF) or inductively coupled plasma optical emission spectroscopy (ICP-OES), atomic absorption spectroscopy (AAS) are likely to be more appropriate techniques.

X-ray diffraction (XRD)

X-Ray Diffraction (XRD) allows identification of the crystalline phases present in substances (primarily inorganic) through comparison of the sample diffraction pattern against a reference database (ICDD). In Figure 8 we see an X-Ray diffraction pattern for sodium chloride with its comparison against a library reference diffraction pattern enabling confirmation of identity and crystal phase.

Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES)

ICP allows the simultaneous multi-element system for the quantitative determination of most of the elements in the periodic table in solution. Typically, it is used to determine the major elements present in a substance. Sample preparation is required which sometimes means acid digestion and dilutions and so dilution factors are introduced. The detection limit typically is around 50 ppb with instrumental uncertainty better than 5% relative.

Ion Chromatography (IC)

Where a substance contains an anionic and cationic part, to confirm the presence of the ions, you need to provide analytical data for the identification and quantification of each ion. IC is often useful for the detection of soluble chloride, fluoride, nitrite, nitrate, bromide, phosphate, and sulfate.


Substance identity testing packages

To achieve a robust registration dossier, it is important to design the right substance identity testing package to completely characterize your substance. It is possible to select from a wide range of different analytical techniques to identify your substance. The starting point is the methods listed in Annex VI however it is important to ask if they are sufficient to confirm the substance identity. Furthermore, what additional techniques would be suitable?

Under EU REACH the SIEF generated a Substance Identity Profile (SIP) which defined the boundary composition of the substance being registered and the identity of any key impurities. The SIEF would also sometimes recommend which analytical techniques to include in your testing package.

Sometimes identity testing is a 2-stage or 3-stage process for the more complicated substances. The data generated through the analyses using the standard methods are reviewed and additional specific analyses are recommended. For UVCB substances such as petroleum substances, for example, there are completely different, specialized analytical requirements. For UVCB substances the raw materials and manufacturing process are part of the substance identity.


The aim of the REACH substance identity test is to prove the identity of the substance you want to register. Structural and purity analytical data is required. This is not always straightforward and may be achieved in multiple stages with the data being refined at each stage. If it is not possible to determine the identity of the substance, the dossier will not be processed.