Paragraph 9 EXPRESSION OF RESULTS

For the EEC fertilisers to which the method is applicable (5 g of fertiliser in 500 ml of extract), the percentage content of the fertiliser is:

$$\mathrm{MgO}\left(\mathrm{\%}\right)\mathrm{in}\mathrm{the}\mathrm{fertiliser}=\genfrac{}{}{0.1ex}{}{\left(\mathrm{b}-\mathrm{a}\right)\times \mathrm{T}}{\mathrm{M}}$$ $$\mathrm{Mg}\left(\mathrm{\%}\right)\mathrm{in}\mathrm{the}\mathrm{fertiliser}=\mathrm{——}-\mathrm{—}-\mathrm{—}\genfrac{}{}{0.1ex}{}{\left(\mathrm{b}-\mathrm{a}\right)\times \mathrm{Tl}}{\mathrm{M}}$$

where:

• a = the volume in millilitres of 0.05 M EDTA solution used for the titration in the presence of calcein or calcon carbonic acid.

• b = the volume in millilitres of 0.05 M EDTA solution used for the titration in the presence of Eriochrome black-T.

• M = the mass of the sample present in the aliquot taken (in grams).

• T = 0.2016× molarity of the EDTA solution/0.05 (see 4.2).

• Tl = 0.1216× molarity of the EDTA solution/0.05 (see 4.2).