The soils fortified with 5 m g g ?1 of chlorpyrifos were extracted
after incubation for 40 days with 1 M NaOH, 30 mL water, followed
by30 mL methanol:water (60:40) and 10 mL 5 M sodium hydroxide
to determine the amount of 14 C present in the different pools. Thehighest amount of 14 C was found in the 1 M NaOH extract (18e30.6%) and water þ methanol (19.4e33.9%), followed by 5 M NaOH(14.1e20.2%), and water (1.7e3.1%) (Fig. 2)