A stock solution of 100 lgmL1 of thiram was prepared by dissolving
0.0100 g of pure thiram (Merck) in ethanol and diluting to
100 mL in a volumetric flask. Working standard solutions were
obtained daily by successive dilutions of this stock solution. A
0.10 mol L1 ethanolic KOH solution (Merck) was prepared by dissolving
0.561 g of KOH in ethanol and diluting to 100 mL. A stock
solution of copper (II), 1000 lgmL1, was prepared by dissolving
of 0.391 g CuSO45H2O (Merck) in water and diluting to 100 mL.
Copper (II) working standard solutions were prepared daily by
stepwise dilution of the stock solution.