Surface-enhanced resonance Raman spectroscopy as an ancillary high-performance liquid chromatography dectector for nitrophenol compounds

Abstract

In this study, the potential application of surface-enhanced resonance Raman scattering (SERRS) spectroscopy as an off-line secondary detector for HPLC has been evaluated. Four nitrophenol compounds, 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, and 4,6-dinitrocresol were separated by isocratic reverse-phase high-performance liquid chromatography (RP-HPLC) and monitored with a conventional UV detector. Resonance Raman (RR) and SERRS spectroscopy were next used to provide the required specificity for distinguishing the nitrophenol compounds. The SERRS detection limit for both 2-nitrophenol and 4-nitrophenol was calculated to be 14 ppb and that for 2,4-dinitrophenol and 4,6-dinitrocresol was estimated to lie near the parts-per-billion level as well. This detection limit is 2-3 orders of magnitude lower than that obtained by RR spectroscopy.

Adsorption analysis of nitrophenol isomers on silver nanostructures by surface-enhanced spectroscopy

“…One SEIRA study by Merklin and Griffiths involved the NP isomers [25], while Kumar and Carey used resonance Raman to characterize each of the NP isomers [26]. A number of SERS studies have also been published involving one or more of the NP isomers [4,[27][28][29][30][31].…”

“…Early SERS [28] and SEIRA [25] work suggested that 4NP adsorbed to silver as a nitrophenolate ion through the oxygen of the phenolate group (PhO À ) instead of the NO 2 group. Later work by Tanaka et al used SERS and density functional theory calculations to propose that 4NP adsorbed to silver through the NO 2 group without a loss of hydrogen associated with the hydroxyl group [27].…”

Effect of Foreign Molecules on the SERS of Probe Molecules Trapped in Gaps between Planar Ag and Nano-sized Ag Particles

“…We can indeed observe the development of Raman peaks of 4-NP; the assignment of Raman spectrum of 4-NP can also be found in the literature. [39][40][41] These peaks must be due to 4-NP inside the nanogaps, indicating that 4-NP molecules can readily diffuse inside the P4VP film. The Raman intensity of 4-NP at 1327 cm −1 (denoted by an asterisk (*) in Figure 6(a)) versus the flow time of 4-NP is shown in Figure 6(b); the Raman intensities were normalized with respect to that of a silicon wafer at 520 cm .…”

Teaching Raman Spectroscopy in Both the Undergraduate Classroom and the Laboratory with a Portable Raman Instrument

“…Further, each experiment presented here could easily be incorporated into more comprehensive experiments recently demonstrated in several articles using similar Raman instruments. [15,37,40] For instance, the thought that portable Raman instrumentation could be coupled with liquid chromatographic techniques [44] to enhance the specificity of detection is attractive for educational purposes.…”