Detection of perchlorate using Ag/DMAH+ SERS-active capture matrices

• Silver colloidal particles were immobilized on amine-derivatized magnetic microparticles.
• The silver colloid was reacted with a thiol to form a self-assembled monolayer (SAM) selective for perchlorate.
• The thiol was dimethylaminoethanethiol hydrochloride.
• The SERS response of the capture matrices were compared to that of conventional SERS substrates.
• The use of solid phase extraction (SPE) to eliminate chloride ion interference was explored.

In this communication, the fabrication of SERS-active capture matrices for the detection of perchlorate is described. The amine groups of amine-modified magnetic microparticles were used to immobilize silver colloidal particles. Once immobilized, the silver was reacted with dimethylaminoethanethiol hydrochloride (DMAH+Cl−) to form a self-assembled monolayer (SAM). The DMAH+ SAM exhibits reasonably good selectivity for perchlorate. It was shown that calibration curves could be generated by ratioing the perchlorate peak with a DMAH+ peak that did not change upon interaction with the perchlorate ion. Flow experiments, using Ag/DMAH+ capture matrices held in place by a magnet, showed instantaneous response to changes in perchlorate concentration. The use of solid phase extraction (SPE) to eliminate chloride ion interference was explored.

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