Surface-enhanced Raman scattering of perchlorate on cationic-modified silver nanofilms – Effect of inorganic anions

Trace‐level perchlorate analysis of impacted groundwater by elevated gold ellipse dimer nanoantenna surface‐enhanced Raman scattering

“…The origin of this frequency shift is unclear; however, it may correspond to ion‐pairing phenomena between ClO 4 − molecules and other ions or the dimethyl‐amino head group of the DMAET coating within the active region of the SERS sensors. This frequency shift has been previously observed for the SERS detection of ClO 4 − and does not impede the successful detection of ClO 4 − . Further study is needed to fully elucidate the origin of this behavior.…”

“…The effect of individual coexisting ions on the SERS detection of ClO 4 − has been explored in detail by Hao et al [2015] for a SERS architecture involving a cysteamine functionalized Ag nanoparticle film on roughened Cu foil . They reported that SO 4 2− exhibited the greatest interference effect of the five ions tested (HCO 3 − , NO 3 − , H 2 PO 4 − , Cl − , and SO 4 2− ) which is well explained by the earlier ion‐pairing constants reported by Mosier‐Boss and Lieberman for these anions with cysteamine .…”

“…The effect of individual coexisting ions on the SERS detection of ClO 4 − has been explored in detail by Hao et al [2015] for a SERS architecture involving a cysteamine functionalized Ag nanoparticle film on roughened Cu foil . They reported that SO 4 2− exhibited the greatest interference effect of the five ions tested (HCO 3 − , NO 3 − , H 2 PO 4 − , Cl − , and SO 4 2− ) which is well explained by the earlier ion‐pairing constants reported by Mosier‐Boss and Lieberman for these anions with cysteamine . While the findings of Hao et al are very informative for predicting the interferences from individual ions on the SERS detection of ClO 4 − , their results differ slightly from the earlier reported findings of Gu et al [2009] and Mosier‐Boss and Putnam [2014], both of whom did not observe interference from SO 4 2− for DMAET functionalized SERS sensors, even though the ion‐paring constant between DMAET and SO 4 2− is greater than the value for DMAET–ClO 4 − .…”

“…There are several literature reports of ClO 4 − detection by SERS at a detection limit lower than or equal to the 0.4‐μM level observed for the elevated Au ellipse dimer structures; for example, Hao et al [2012] report a detection limit of 5 µg l −1 (~0.05 μM) using cysteamine functionalized Ag films on roughened Cu foil . However, the performance of the elevated Au ellipse dimer architectures reported here was determined with a portable Raman instrument, as the ultimate goal of this approach is to demonstrate field‐scale measurements, which has inherently lower detection efficiency than the bench‐top Raman microscopes typically used in SERS measurements (see Supporting Information, Fig.…”

“…The systematic quantification of interferences in SERS is vital for analyzing complex samples as the SERS technique is non‐specific and will report on any Raman active compounds within the working region of the sensor. However, there are few reported studies which explore interferences for SERS analysis of groundwater . Finally, we demonstrate successful determination of ClO 4 − contamination at the micromolar level within impacted groundwater collected from a United States Department of Defense (DoD) site, indicating the applicability of this approach for field measurements.…”