Novel Approach to Enrich Nicotine in Plasma for Rapid High Performance Liquid Chromatographic Analysis Using Three-Phase Hollow Fiber Based Liquid Phase Microextraction

A novel method for the quick determination of nicotine in plasma was established by using high performance liquid chromatography (HPLC) coupled with a three-phase hollow fiber based liquid phase microextraction (TP-HF-LPME) technique for sample preparation. The microextraction was mediated by the pH difference between the environment inside and outside of an organic phase immobilized in the pores formed in the wall of a polypropylene hollow fiber. The pH value of the medium outside the organic phase was adjusted by adding a dilute KOH solution to form a basic donor phase, whereas the pH value of the inner media was set to pH 3 to form an acceptor phase using a 10 mmol/L KH2PO4 solution. Under working conditions, neutral nicotine molecules were first extracted from the original sample solution to the organic phase, and then the analyte was extracted from the organic phase to the acceptor phase. After the described extraction time, 4 μL of the acceptor phase was withdrawn and injected into the HPLC for analysis. The parameters related to TP-HF-LPME (organic solvent, pH of acceptor and donor phase, stirring rate, salt effect, methanol content in acceptor phase, and extraction time) were also optimized experimentally. The proposed method integrates extraction, enrichment, and clean-up into a single step, thus dramatically simplifying the traditional procedure to prepare a liquid sample with complex matrix such as plasma. It has been proved to be a very quick, effective, and virtually “green” sample preparation technique, which provides a good linear range (0.1–50 mg/L) with r2 = 0.9996, a low detection limit (0.05 mg/L, S/N = 3), and a satisfactory relative standard deviation (< 5%).