Issue 13, 2020

Novel SERS-based process analysis for label-free segmented flow screenings

Abstract

In microfluidic segmented flow processes label-free analytical techniques like surface enhanced Raman spectroscopy (SERS) can reveal the chemical composition of the individual droplet contents. The SERS system developed in this work enables a simple connection to micro segmented flow processes through miniaturization. The concept is based on the parallelization of silver/polyacrylamide composite SERS spots on a carrier plate on which the segments are deposited. The transfer of the segments allows an easy connection to existing flow processes and provides optimal conditions for Raman measurements using miniaturized spectrometers. The preparation of the SERS polymer composite was optimized in terms of the silver content in the polymer matrix to obtain a high SERS signal. The performance and long-term stability of the polymer have been successfully demonstrated. The deamination of adenine with sodium nitrite to hypoxanthine was chosen as a case study to demonstrate the capability of the novel SERS-based process analysis. A sequence of approximately one hundred segments in combination with a gradient of the nitrite concentration (0 to 0.4 mol L−1) was generated at two temperatures. The concentration of adenine and hypoxanthine were determined by using a multivariate calibration model, since the Raman spectra of both substances are overlapping. It was shown that the conversion of adenine is increased with higher nitrite concentration and temperature. A conversion of 35% was obtained at 50 °C and a conversion of 60% at 80 °C, respectively.

Graphical abstract: Novel SERS-based process analysis for label-free segmented flow screenings

Supplementary files

Article information

Article type
Paper
Submitted
09 Apr 2020
Accepted
28 May 2020
First published
29 May 2020
This article is Open Access
Creative Commons BY-NC license

Lab Chip, 2020,20, 2364-2371

Novel SERS-based process analysis for label-free segmented flow screenings

A. Mendl, J. M. Köhler, D. Bošković and S. Löbbecke, Lab Chip, 2020, 20, 2364 DOI: 10.1039/D0LC00367K

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