Portable kit for high-throughput analysis of polycyclic aromatic hydrocarbons using surface enhanced Raman scattering after dispersive liquid-liquid microextraction

In this work, a portable kit was developed for convenient high-throughput trace analysis of polycyclic aromatic hydrocarbons (PAHs) using surface enhanced Raman scattering (SERS) after dispersive liquid-liquid micro extraction (DLLME) process. This portable kit contains three sealed reagent tubes (labeled as T1, T2 and T3), a self-made well plate, and a portable Raman spectrometer. The reagent tube T1 contains a mixture of disperser solvent and extraction solvent, which involved a 2 min sample pretreatment of DLLME process. The quick injection of solvents in tube T1 into the sample containing PAHs formed a cloudy solution immediately, which consists of fine droplets of extraction solvent dispersed entirely into aqueous phase. The enrichment factor was found to be 29.6. T2 and T3 contain methanol and 1-propanethiol-modified silver nanoparticles (PTH-Ag NPs), respectively. The liquid in the tube T3 was used to enhance the Raman signal of analytes on the self-made high-throughput micro reactor. A linear relationship between the concentration of pyrene and the relative Raman peak intensity was obtained (R-2 = 0.993). The detection limit was 0.50 mu g L-1 for pyrene. RSD of the high-throughput analysis of 12 samples was calculated as 4.8%. The ability of DLLME-SERS technique in the extraction of PAH isomers from water samples were investigated. The performance of DLLME-SERS in the recovery of pyrene from lake, spring and drinking water was also studied.