Low-temperature sorption-luminescence determination of platinum using silica chemically modified with N-allyl-N'-propylthiourea and N-phenyl-N'-propylthiourea

Silicas chemically modified with N-allyl-N'-propylthiourea and N-phenyl-N'-propylthiourea were proposed for the low-temperature sorption-luminescence determination of platinum. The sorption of platinum(II) and platinum(IV) at the surface of sorbents yields coordination compounds luminescing at 77 K under UV irradiation. Luminescence spectra of platinum(II) complexes of thiourea derivatives covalently bonded to the silica surface exhibit a broad structureless band with a maximum at 585 nm. For the sorbent with N-allyl-N'-propylthiourea groups, the detection limit of platinum is 0.1 μg per 0.1 g of the sorbent. The calibration plot is linear up to 50 μg/0. I g. The detection limit and the linearity range of calibration plots depend on the mass of the sorbent. The proposed procedure was used for the analysis of aluminoplatinum catalysts.