ATTACHMENT 1: IONIC MIXTURES23

In order to provide a specific physicochemical characteristic, water is added to mixtures of ionic substances (salts, acids and bases). The ionic pairs in equilibrium in the aqueous solution are then the result of the water functioning as intended and would consequently not be considered to be themselves manufactured, imported or placed on the market and may under well defined conditions qualify for an exemption under entries 3, 4(a) or 4(b) of Annex V as explained hereafter. 

In order for this exemption to be applicable, the following conditions must be fulfilled: 

• All starting substances (salts, acids and bases) of the aqueous solution must be registered; 
  
• None of the salts in the aqueous solution is isolated from the solution; and 
  
• The salts remain in their ionic form in the solution. 

These three conditions equally apply to imported solutions. In particular, this requires that all starting substances of the imported solution must be known and registered in the EU; otherwise the exemption does not apply. 

The latter two conditions must also be fulfilled by any customer down the supply chain. If a customer removes any salt from the solution his/her role as downstream user is ending here and he/she becomes a manufacturer which must register the isolated substances. 

For solutions of salts in water no registration is required of ionic pairs as long as the combinations of ions co-exist with their different equilibria in the solution and no salts are isolated. In this context, it might be useful to clarify that 

• whenever ionic pairs exist only as a part of the chemical equilibrium in the aqueous solution, they are not themselves considered to be manufactured, imported or placed on the market and thus do not require registration.  
• whenever a salt is isolated from the solution, it is manufactured and needs to be registered.

23 Substances ionised in water, CARACAL/05/2009 first Meeting of the Competent Authorities for REACH and CLP (CARACAL), 16-17 March 2009, Centre A. Borschette Rue Froissart 36, 1040 Brussels, Belgium. 

 3 - deliberate neutralisation of acids or bases to form the corresponding salts, including neutralisation during formulation, is usually a manufacturing process and is not covered by this exemption. 

It should be noted that although the registration of substances ionised in water as described above is deemed inappropriate and is therefore exempted, the potential risks associated with the substances ionised in water must be taken into account in the chemical safety assessment of the starting materials (i.e. salts, acids or bases introduced in the aqueous solution), where applicable. 

In some cases, there are water solutions that are manufactured by mixing many different kinds of substances (e.g. salts, acids, bases) in water. One example of this can be a detergent used as all-purpose cleaner. A formulation of such a product can contain the following substances (First list): 

• Sodium lauryl ether sulphate 
  
• (Linear) alkylbenzene sulphonic acid 
  
• Oleic acid 
  
• Nitrilotriacetic acid (NTA) 
  
• Phosphoric acid 
  
• Citric acid 
  
• Sodium hydroxide 
  
• Potassium hydroxide 

Non-ionic surfactant, preservative, dyes, fragrance: do not participate to acid/base equilibria 

In this case, some salts, acids and basis are mixed in different proportions in order to achieve a product with a certain surfactant properties. As a consequence of the dissolution of the different substances, the different cations and anions find an equilibrium state forming pairs of ions. In the example shown above, it is theoretically possible to identify 12 anions and 2 cations. In this case, more than 40 substances may theoretically coexist in solution. Some of them may be the same as the precursor substances. A non-exhaustive list of potential substances in solution (based on acid- base reactions/equilibria achieved via the protolytic reactions with water) that could be formed in addition of the above-mentioned ingredients (and identified only if water is removed) is shown below (Second list): 

• Sodium alkylbenzene sulphonate 
  
• Potassium alkylbenzene sulphonate 
  
• Trisodium citrate 
  
• Disodium citrate 
  
• Monosodium citrate 
  
• Tripotassium citrate
  
• Dipotassium citrate 
• Monopotassium citrate 
  
• Monosodium, monopotassium citrate 
  
• Sodium oleate 
  
• Potassium oleate 
  
• Sodium phosphates 
  
• Potassium phosphates 
  
• Potassium lauryl ether sulphate 
  
• Potassium salt of NTA 

Adding one more base (e.g. ammonia) to the formulation would lead to an even greater number of potential ion pairs in solution. 

As long as the salts in solution remain stable in their ionic form in the solution and are not isolated from it, it is only necessary to register the precursors (first list) but not the potential substances that may be formed in a solution (second list).