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

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 Inic/Ipyr against the concentration of nicotine were non-linear but plotting Inic/Ipyr 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.