In vitro test method must be suitable for the particular domain/formulation being tested. The selection of in vitro methods must be in line with Article 8(3) of CLP, i.e. be listed in the EU Test Methods Regulation or being a method internationally recognised. Some methods are validated only for certain effects/classification bands, this can be a limitation. In addition, not all laboratories are equipped to perform all tests. If the company has many mixtures to classify, this will take time (several weeks) and be expensive.