Standard Addition Method Applied to the Urinary Quantification of Nicotine in the Presence of Cotinine and Anabasine Using Surface Enhanced Raman Spectroscopy and Multivariate Curve Resolution

In this work, urinary nicotine was determined in the presence of the metabolite cotinine and the alkaloid anabasine using surface enhanced Raman spectroscopy and colloidal gold as substrate. Spectra were decomposed using the multivariate curve resolution-alternating least squares method, and pure contributions were recovered. The standard addition method was applied by spiking urine samples with known amounts of the analyte and relative responses from curve resolution were employed to build the analytical curves. The use of multivariate curve resolution in conjunction with standard addition method showed to be an effective strategy that minimized the need for reagent and time-consuming procedures. The determination of the alkaloid nicotine was successfully accomplished at concentrations 0.10, 0.20 and 0.30 μg mL(-1) and total error values less than 10% were obtained.