The Fertilisers (Sampling and Analysis) Regulations 1996

“8.2    DETERMINATION

Titration in the presence of Eriochrome black-T.

Pipette an aliquot portion (8.1) of the solution to be analysed into a 400 ml beaker. Neutralise the excess acid with the 5 M sodium hydroxide solution (4.12) and check the pH. Dilute with water to approximately 100 ml. Add 5 ml of the buffer solution (4.9). The pH measured by 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). Titrate with the EDTA solution (4.2). Stirring gently with the stirrer (5.1) (see 10.2, 10.3 and 10.4). Let ‘b’ be the volume in millilitres of 0.05 molar EDTA solution used.