Test solutions
13. Test solutions of the chosen concentrations are prepared by dilution of a stock solution. Stock
solutions of substances of low water solubility may be prepared by ultrasonic dispersion or other
suitable physical means. If necessary, vehicles such as organic solvents, emulsifiers or dispersants of
low toxicity to fish may be used. When such vehicles are used an additional control should be
exposed to the same concentration of the vehicle as that used in the most concentrated solution of the
test substance. The concentration of organic solvents, emulsifiers or dispersants should not exceed 100
mg/l.