The Fertilisers (Sampling and Analysis) Regulations 1996 No. 1342

SCHEDULE 2 METHODS OF ANALYSIS

PART I

14d. DETERMINATION OF THE pH VALUE

Buffer solution, pH 4.00 at 20° C

3.2  Dissolve 10.21+0.01 grams of potassium hydrogen phthalate (KHC₈O₄H₄) in water, transfer without loss into a 1 litre standard flask, make up to the mark and mix.

Keep this solution in an airtight vessel.