Doda se 5 ml pufrske raztopine (4.9). pH, izmerjen z metrom, mora biti 10,5 ± 0,1. Dodata se 2 ml raztopine kalijevega cianida (4.7) in tri kapljice indikatorja eriokrom črnega T (4.6).
Add 5 ml of the buffer solution (4.9). The pH measured by the meter must be 10,5 ± 0,1. Add 2 ml of the potassium cyanide solution (4.7) and three drops of the eriochrome black-T indicator (4.6).