Compositional Analysis of Ternary and Binary Chemical Mixtures by Surface-Enhanced Raman Scattering at Trace Levels

Abstract

Surface-enhanced Raman scattering has been proven a powerful means in the fast detection and recognition of chemicals at trace levels, while quantitative analysis especially the compositional analysis of trace chemical mixtures remains a challenge. We report here a “triangle-rule” based on the principal component analysis (PCA) of surface-enhanced Raman scattering spectra, to calculate the composition of individual component of ternary chemical mixtures at trace levels, which can be simplified into the “balance-rule” for binary mixtures. We demonstrated the validity of the triangle-rule and balance-rule in estimating the composition of ternary and binary mixtures of methyl orange, methylene blue, and crystal violet with different molecular structures, and the validity for ternary and binary mixtures of three isomers of monochlorobiphenyl with very similar molecular structures. This idea might be also applicable to mixtures of more components at the trace levels.

Ag Nanorods-Based Surface-Enhanced Raman Scattering: Synthesis, Quantitative Analysis Strategies, and Applications

“…For example, Shanmukh et al demonstrated that three different respiratory syncytial virus strains were able to be differentiated by PCA using their PCA scores as shown in Figure 8A (Shanmukh et al, 2008). Recently, our group proposed a simple way to estimate compositions for binary and ternary chemical mixtures employing PCA and SERS (Hou et al, 2015a). As differences between the chemical compositions adsorbed on substrates and that in solution was neglected which is not suitable for most cases, we modified that method in order to provide a general route for the compositional analysis by considering the difference in chemicals' adsorption abilities in trace level solution (Zou et al, 2017).…”

A Review of Chinese Raman Spectroscopy Research Over the Past Twenty Years

“…On the basis of evaluating the validity of the triangular rules and the equilibrium rules composed of ternary and binary mixtures of methyl orange, methylene blue, and crystal violet with different molecular structures, it was verified that the ternary and binary mixtures of the three isomers of chloroform are very similar in molecular structure. 76 They also achieved the research and development of stable and recyclable SERS substrates such as SiO 2 @Au nanorod arrays and Ag nanorods coated with Al 2 O 3 or TiO 2 film, which was applied to detect 5 µg/g polychlorinated biphenyls in soil samples. 77…”

Semi-quantitative analysis of multiple chemical mixtures in solution at trace level by surface-enhanced Raman Scattering

“…treating the composition measured for chemicals adsorbed on the nanorods as the same in solution) 30 . This assumption is of course not correct for most chemical mixtures in solution, but it opens a simple and new route for quantitative analysis (specifically the compositional analysis) if we could find a way to properly consider the difference in the adsorption kinetics of chemicals in trace level solution.…”

“…Recently, we performed and device a simple way to estimate the composition of chemicals adsorbed on Ag@SiO 2 nanorods as the SERS substrate by PCA (which is normally used for discriminating molecules), and prove it experimentally through several trace-level chemical mixtures in solution, by neglecting the difference in their adsorption kinetics (i.e. treating the composition measured for chemicals adsorbed on the nanorods as the same in solution) 30 . This assumption is of course not correct for most chemical mixtures in solution, but it opens a simple and new route for quantitative analysis (specifically the compositional analysis) if we could find a way to properly consider the difference in the adsorption kinetics of chemicals in trace level solution.…”