In previous work [6,7], we have demonstrated the feasibility of a
preconcentration procedure using the commercial anionic exchanger
Aliquat 336 (a quaternary ammonium salt) for the isolation of Cd
contained in liquid samples. Activated membranes were prepared by
impregnating the pores of a polyvinylidene difluoride (PVDF) support
with a solution of 500mMof Aliquat 336 in decaline for 10 min. These
membranes were then taken out of the organic solution and wiped
with a piece of filter paper.