Paragraph 7 EXPRESSION OF RESULTS

1 ml of standard sodium thiosulfate solution (4.5) corresponds to 2 mg Cu.

The percentage of copper in the fertiliser is given by:

$$\mathrm{Cu}\left(\mathrm{\%}\right)=\mathrm{X}\times \mathrm{—————}\genfrac{}{}{0.1ex}{}{\mathrm{V}}{\mathrm{a}\times \mathrm{M}\times 5}$$

where:

• X is the volume in ml of the sodium thiosulfate solution used;

• V is the volume in ml of the extract solution in accordance with Methods 26a and 26b;

• a is the volume in ml of the aliquot portion;

• M is the mass in g of the test sample treated in accordance with Methods 26a or 26b.