High-throughput determination of nicotine in plasma by ultrasonication enhanced hollow fiber liquid-phase microextraction prior to gas chromatography.

In high-throughput ultrasonication enhanced hollow-fiber liquid-phase microextraction (H-U-HF-LPME), ultrasonication was introduced into HF-LPME to enhance the mass transfer rate of the analytes in the two immiscible liquid phases, which resulted in a very short time for extraction equilibrium and a high-throughput analysis. Several parameters were investigated and optimized (such as extraction solvent, temperature of sample, frequency and intensity of ultrasonication, volume of extractant, extraction time, ionic strength of the sample and sample concentration). Based on the results of this study, nicotine was first extracted from a 1.5 mL sample solution under the optimum conditions (ultrasonic power of 50 W with a frequency of 60 kHz, extraction time of 10 min, sodium chloride concentration of 5 mol/L and temperature of 37°C). Next, 0.5 µL of acceptor solution inside the hollow fiber was automatically injected into a gas chromatograph with a flame ionization detector. The results of this study illustrated that the limit of detection, relative standard deviation (n = 6), relative recovery and enrichment factor of nicotine were 0.06 µg/L, 3%, 99.8% and 16.6, respectively. Finally, H-U-HF-LPME was successfully applied for the determination of nicotine in plasma.