Detection of hexavalent chromium using gold/4-(2-mercaptoethyl) pyridinium surface enhanced Raman scattering-active capture matrices

• We prepared capture matrices specific for hexavalent chromium.
• Capture matrices were prepared by immobilizing gold colloidal particles on amine-derivatized magnetic microparticles.
• The gold colloid was reacted with a thiol to form a SAM selective for hexavalent chromium.
• The thiol was 4-(2-mercaptoethyl) pyridinium (MEP) hydrochloride.
• The SERS response of the capture matrices was compared to that of conventional SERS substrates.

In this communication, the fabrication of SERS-active capture matrices for the detection of hexavalent chromium is described. The amine groups of amine-modified magnetic microparticles were used to immobilize gold colloidal particles. Once immobilized, the gold was reacted with 4-(2-mercaptoethyl) pyridinium (MEP) hydrochloride to form a self-assembled monolayer (SAM). The MEP SAM exhibits great selectivity for hexavalent chromium. It was shown that calibration curves could be generated by ratioing MEP peaks that increased in intensity upon complexation with chromate with a peak that did not change. Flow experiments, using Au/MEP capture matrices held in place by a magnet, showed instantaneous response to changes in chromate concentration.

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