Mix the contents thoroughly by carefully tilting the cylinders backwards and forwards several times (care being taken to lift the stopper in occasionally). Leave for 10 minutes at room temperature and then put in the water bath (5.3) at 20 ± 0,5 °C. After 20 minutes pour the contents into a series of spectrophotometer cuvettes.
Après 20 minutes, verser le contenu des tubes dans des cuves de spectrophotométrie.