Application of Response Surface Methodology for Pipette-Tip Micro Solid-Phase Extraction of Nicotine from Cigarette, Seawater and Human Plasma by a Novel Carbon Nanotube/Zinc Oxide Nanocomposite Sorbent Following its Determination by Spectrophotometry

This research describes the application of response surface methodology (RSM) to develop a miniaturized carbon nanotube/zinc oxide nanocomposite as a novel sorbent for pipette-tip solid-phase microextraction for the preconcentration of nicotine from different complex matrices and its determination by spectrophotometry. Extracted nicotine reacted with potassium permanganate in the presence of sodium hydroxide to form a water-soluble green product which has a maximum absorbance at 610 nm. The effects of various parameters affecting microextraction such as the type and amount of salt, type and amount of sorbent, type and volume of eluent, sample volume and number of cycles of extraction and elution were optimized using both one-variable-at-a-time technique and RSM. The linear range of investigated method was 1.0–150 µg/L for nicotine. The detection limit for the analyte of 0.3 µg/L was achieved. Reproducibility of the protocol (expressed as RSD) was better than 4.8%. The technique was successfully applied to the determination of nicotine in seawater, human plasma and cigarette.