Rapid, quantitative analysis of ppm/ppb nicotine using surface-enhanced Raman scattering from polymer-encapsulated Ag nanoparticles (gel-colls)

Abstract

Rapid, quantitative SERS analysis of nicotine at ppm/ppb levels has been carried out using stable and inexpensive polymer-encapsulated Ag nanoparticles (gel-colls). The strongest nicotine band (1030 cm⁻¹) was measured against d₅-pyridine internal standard (974 cm⁻¹) which was introduced during preparation of the stock gel-colls. Calibration plots of I_nic/I_pyr against the concentration of nicotine were non-linear but plotting I_nic/I_pyr against [nicotine]^x (x = 0.6–0.75, depending on the exact experimental conditions) gave linear calibrations over the range (0.1–10 ppm) with R² typically ca. 0.998. The RMS prediction error was found to be 0.10 ppm when the gel-colls were used for quantitative determination of unknown nicotine samples in 1–5 ppm level. The main advantages of the method are that the gel-colls constitute a highly stable and reproducible SERS medium that allows high throughput (50 sample h⁻¹) measurements.