This application note describes a fast and simple method for removing rhodium using StratoSpheres™ SPE columns. StratoSpheres™ SPE columns are self-indicating SPE columns developed by Polymer Laboratories that change color in the presence of certain metal ions, informing the user when the column is nearing its capacity.
This document details the use of PL-Thiol MP SPE and PL-Thiourea MP SPE devices for the effective removal of rhodium residues from organic solutions containing catalysts like Wilkinson's catalyst or rhodium acetate. The sorbents are made from a highly cross-linked macroporous polymer that does not swell and can be used for a range of solvents. They are self-indicating in the presence of certain metal ions, informing the user when the device is nearing its capacity.
The typical procedure involves pre-conditioning the SPE tube with methanol (or a compatible solvent like DCM or THF), adding the catalyst-containing solution to the tube under gravity, and washing the tube with a suitable solvent. The resulting organic solution is then free of metal contamination, as verified by ICP analysis showing final rhodium concentrations below 0.1 ppm.
| Final Rh Conc (ppm) | <0.1 |
|---|---|
| Starting concentrations of Rh catalysts | ~1000 ppm |
The sorbents can be used for a range of protic, non-protic, polar and apolar solvents.
The polymer is specially engineered to be self-indicating in the presence of certain metal ions.