Surface Enhanced Raman Scattering Imaging of Developed Thin-Layer Chromatography Plates

Abstract

A method for hyphenating surface enhanced Raman scattering (SERS) and thin-layer chromatography (TLC) is presented that employs silver-polymer nanocomposites as an interface. Through the process of conformal blotting, analytes are transferred from TLC plates to nanocomposite films before being imaged via SERS. A procedure leading to maximum blotting efficiency was established by investigating various parameters such as time, pressure, and type and amount of blotting solvent. Additionally, limits of detection were established for test analytes malachite green isothiocyanate, 4-aminothiophenol, and Rhodamine 6G (Rh6G) ranging from 10(-7) to 10(-6) M. Band broadening due to blotting was minimal (∼10%) as examined by comparing the spatial extent of TLC-spotted Rh6G via fluorescence and then the SERS-based spot size on the nanocomposite after the blotting process. Finally, a separation of the test analytes was carried out on a TLC plate followed by blotting and the acquisition of distance × wavenumber × intensity three-dimensional TLC-SERS plots.

Rapid on-site detection of ephedrine and its analogues used as adulterants in slimming dietary supplements by TLC-SERS

“…In general, the method developed above may prove to be the optimal choice for separating the four analogues from each other. Although some qualitative information resides in R f of the detected spots, component identification based on R f value is not reliable [31]. However, TLC can be coupled with the spectrometric method such as SERS for compoundspecific information.…”

Determination of Sudan I in paprika powder by molecularly imprinted polymers–thin layer chromatography–surface enhanced Raman spectroscopic biosensor

“…TLC coupled with SERS has been explored for on-line, sensitive and cost-effective detection of chemicals in complex sample matrix [24,[32][33][34]. Ultra-thin layer chromatography was developed by laser ablating silver onto a plate substrate to generate an ultra-thin film of silver that is capable of separating a mixture of a few dyes and enhancing the corresponding Raman signals [24].…”

“…Ultra-thin layer chromatography was developed by laser ablating silver onto a plate substrate to generate an ultra-thin film of silver that is capable of separating a mixture of a few dyes and enhancing the corresponding Raman signals [24]. Freye et al [32] cured polydimethylsiloxane (PDMS) polymers in a mold as the solid phase extractor and physically deposited silver nanoparticles onto the top of PDMS to receive separated compounds transferred from a C 18 silica gel TLC plate. SERS spectra of the separated compounds were recorded.…”

“…SERS spectra of the separated compounds were recorded. Malachite green isothiocyanate, Rhodamine 6G, methylene violet, known as SERS active molecules [24,32], were used to test the performance of TLC-SERS, and the mixture of a few standard amino acids [34] was also tested; in addition, detection of aromatic pollutants in water by TLC-SERS has been reported as well [42]. Real samples were investigated, but sample pre-treatment was necessarily complex because these samples contained significant interferences [33].…”

Instrument platforms for thin-layer chromatography

“…The techniques of resonance Raman spectroscopy and surface enhanced Raman spectroscopy (SERS) have long since promised to solve this problem without great progress, at least not in thin-layer chromatography. SERS, in particular, is a very sensitive technique but requires application of a metal hydrosol to the layer or transfer of the separation to a flexible metal-impregnated substrate to enhance the signal intensity [101]. Both approaches have not moved out of the research phase and dedicated instruments for use with thin-layer chromatography are unavailable.…”