Activity was determined in the presence of each pollutant
at the concentration up to 2 mM. Suitable amounts
of stock solutions in acetone were added to glass tubes
and subjected to slight N2 stream until dryness. In order
to achieve maximum solubility of the test compound,
75 ll of dimethyl sulfoxide as solubilization adjuvant was
used to obtain the final concentration of 7.5%. To guarantee
the effectiveness of this procedure, samples were assayed
together with tubes containing endosulfan and fish liver
acid phosphatase (as a positive control) since this compound
demonstrated a potent inhibition on the enzyme
activity