New strategies for the removal of template from the ion and molecularly imprinted polymers: Application to the fast and on-site Cr(VI) detection with a smartphone

The extraction of templates from MIPs is not an easy task as well known, because of the high affinity between monomers and templates. Herein, a new strategy for the immediate removal of the template was developed. Two polymers were prepared, one for hexavalent chromium (Cr(VI)) and the other for rutin molecule, to overcome the extraction problem for ions and molecularly imprinted polymers. A diphenylcarbazide solution was used for removing Cr(VI), allowing an immediate extraction of this ion from the polymer. For rutin molecule, the aluminum solution allowed fast removal. Since these removal strategies imply extracting with coloration development, these elution solutions could be used simultaneously for the extraction and detection of the analyte. Indeed, an analytical reading kit has been 3D-printed for the Cr(VI) smartphone detection. In this tool, a column containing the ionic imprinted polymer (IIP) was used as sorbent and diphenylcarbazide solution for eluting and detecting Cr(VI). The developed sensor exhibited a detection limit of 0.006 µg mL-1. The proposed procedure was applied successfully for Cr(VI) determination in tap and river waters showing satisfactory recoveries. These extraction methods pave the way for the application of other ligands for the gentle, fast and on-site removal of different templates.