Miniaturized Thermal-Assisted Purge-and-Trap Technique Coupling with Surface-Enhanced Raman Scattering for Trace Analysis of Complex Samples

It still remains a great challenge for quantification of trace analytes in complex samples by surface-enhanced Raman scattering (SERS) technique due to potential matrix influence or weak SERS responses of analytes. In this work, a miniaturized thermal-assisted purge-and-trap (MTAPT) device was designed and developed to eliminate matrix influence coupled with derivatization method before SERS analysis. The design of MTAPT chamber was optimized based on quantitative calculation of its dead volume by computational fluid dynamics simulation. The small straight chamber was selected as an optimized design with a recovery of 96.1% for formaldehyde. The practical feasibility of MTAPT was validated based on four real analytical applications including phenthiol in industrial water, formaldehyde in flour, sulfion in wastewater, and methanol in industrial alcohol. The results showed that SERS responses of all analytes dramatically increased by eliminating sample matrices after MTAPT process. Phenthiol, formaldehyde, sulfion, and methanol in real, samples could be accurately quantified with recoveries of 80.9-110.0%, and the analytical results were validated by corresponding standard, methods. The time consumption of MTAPT-SERS for real sample analysis including sample preparation and determination was within 16 min. It is highly expected that the combination of MTAPT technique with portable SERS instrument can greatly expand the range of SERS analysis. The proposed MTAPT-SERS method has high potential for on-site analysis of complex samples.