Determination of pesticides by capillary chromatography and SERS detection using a novel Silver-Quantum dots “sponge” nanocomposite

In this work the at-line capillary-liquid chromatography-(microdispenser)-surface-enhanced Raman spectroscopy coupling was investigated and applied to the determination of pesticides. The use of a microdispenser combined with the use of a precise and reproducible surface enhanced Raman spectroscopy (SERS) substrate yielded a chromatographic detection system with excellent analytical properties. The microdispenser was coupled to a moving CaF2 hot (80 °C) plate using a flow-through microdispenser interface to collect the microdrops. Ag-QD nanocomposites, which are highly reproducible thanks to their sponge-shaped structure, were used as substrate with which to measure the SERS spectra in each spot of the plate. The limits of detection ranged from 0.2 to 0.5 ng of pesticide injected (chlortoluron, atrazine, diuron and terbuthylazine) and the precision ranged between 10.2 and 12.5%.

► Sensitive at-line surface enhanced Raman detection in capillary chromatography.
► Ag colloid – ZnS/CdSe quantum dot nanocomposite as highly active SERS substrate.
► LODs for the determination of pesticides ranging from 10 to 20 pg.