Highlighting Recent Developments in Raman and More

SciX 2021

The Great SCientific EXchange, Sept. 26-Oct. 1, 2021, Providence, R.I.

Title: Getting LIBS results outside the laboratory: lessons from the field
Author: Steve Buckley, General Manager, Applied Systems
Schedule: Monday, Sept. 27, 2021, 8:30-8:50 a.m. (EDT)
Location: Meeting Room 550 (Fifth Floor)

Title: Enhancing Spectral Repeatability and Limits of Detection Using Liquid Phase Nanoparticles for Quantitative Raman
Author: Derek Guenther, Senior Applications Scientist
Schedule: Monday, Sept. 27, 2021, 2:10-2:30 p.m. (EDT)
Location: Meeting Room 558 (Fifth Floor)
Abstract: As the pandemic has fueled the need for new, rapid detection methods, much of the focus has been on optical techniques for their speed and portability. One detection method that has seen much growth and commercial adoption over the last decade is SERS, or Surface-Enhanced Raman Spectroscopy. While SERS consumable substrates are offered in a variety of flavors and form factors from many suppliers, one inherent limitation to all is their repeatability within and between production batches. A separate approach is presented here that leaves the signal-enhancing nanoparticles in aqueous suspension and allows the analyte interaction and Raman enhancement to occur in the liquid phase.

Title: Water Hardness Assessed with Liquid Surface-Enhanced Raman Spectroscopy (LSERS)
Author: Amy Bauer, Principal Applications Scientist (presenter); and Derek Guenther, Senior Application Scientist, and Yvette Mattley, Lab Services Manager (non-presenting authors)
Schedule: Tuesday, Sept. 28, 2021, 10:10 a.m.-3:50 p.m. (EDT)
Location: Poster Session, Exhibit Hall C (Third Floor)
Abstract: Surface-enhanced Raman spectroscopy (SERS) has been a topic of interest in the analytical chemistry and spectroscopy communities for many years. Although commercially produced substrates are available for the performance of various types of analyses, expansion of the use of the technique has been hampered by the lack of reproducibility. It is generally recognized that this issue is rooted in challenges surrounding nanoparticle deposition on substrate material.

An alternative approach is to leave the signal-enhancing nanoparticles in aqueous suspension and allow the analyte interaction and Raman enhancement to occur in the liquid phase. We observe greater repeatability in both native gold and silver nanoparticle background signals and the subsequent analyte signal return with the liquid than with the substrate approach. An additional benefit to the use of the suspension is that more laser power can be brought to bear on the measurements without fear of burning substrate materials. Using this approach, useful Raman spectra of a variety of organic compounds have been acquired to the part-per-billion level.

This presentation documents the analysis of hardness in mineral water as a surrogate for other inorganic constituents and contaminants in water. Mineral water samples instilled into 2 ml vials of gold nanoparticles in aqueous suspension have been interrogated with a 785 nm laser and signals collected with an Ocean Insight QE Pro Raman system. Curves of growth, limits of detection, and other measurement statistics will also be presented.