A palladium ion imprinted polymer (Pd IIP) with nanopores, capable of preconcentrative separation of Pd, has been synthesised by a team from CSIR, India (S. Daniel, J. M. Gladis and T. Prasada Rao, Anal. Chim. Acta, 2003, 488, (2), 173–182). The Pd IIP was synthesised by the thermal copolymerisation of Pd(II)–dimethylglyoxime–4-vinyl- pyridine ternary complex, styrene and divinylbenzene in the presence of 2,2′-azobisisobutyronitrile as initiator. IIP particles were obtained using cyclohexanol as the porogen, followed by leaching with 50% HCl to remove the Pd.

In tests, the IIP could extract Pd ions from dilute aqueous solutions. The IIP particles had much higher selectivity towards Pd over Pt and base metals found in noble metal deposits, and 100 times higher distribution ratio than an ion recognition (blank) polymer. Also, γ-irradiation was found to enhance the extraction of Pd particles into leached IIP particles compared to unirradiated ones.