Development of a passive sampler for Zinc(II) in urban pond waters using a polymer inclusion membrane

The use of a polymer inclusion membrane (PIM) in a novel passive sampler to measure the time-weighted average concentration of Zn(II) in urban waters is described. The passive sampler consists of a compartment containing an acidic receiving solution, which is separated from the external source solution by a PIM consisting of 40 wt% di-2-(ethylhexyl) phosphoric acid as the extractant, and 60 wt% poly-(vinyl chloride) as the base polymer. Two laboratory passive sampling techniques were tested. One involved immersion of the passive sampler into a source solution ("dip-in" approach) for a predetermined period of time while in the other one the source solution was flown past the membrane of the sampler ("flow-through" approach). The latter approach was found to be more suitable for the calibration of the passive sampler under laboratory conditions. A successful application using the "dip-in" sampling approach in urban waters has been conducted for proof of concept.