During the analysis, unless otherwise stated, use only reagents of recognised analytical grade and distilled or demineralised water or water of equivalent purity.

Solvent: Iso-octane (2,2,4 trimethylpentane) for the measurements at 232 nm and 268 nm and cyclohexane for the measurements at 232 nm and 270 nm, having an absorbance less than 0,12 at 232 nm and less than 0,05 at 270 nm against distilled water, measured in a 10 mm cell.