Simultaneous enrichment and analysis of tobacco alkaloids by microextraction coupled with mass spectrometry using a poly (N-isopropyl-acrylamide-co-divinyl-benzene-co-N, N'-methylene diacrylamide) monolithic column

Abstract

Herein, we realized the simultaneous online detection of six tobacco alkaloids (TAs) by in-tube solid-phase microextraction (In-tube SPME) coupled with mass spectrometry by a rapid, sensitive, and matrix effect–free method requiring no chromatographic separation and only minimal sample pre-treatment. A poly (N-isopropylacrylamide-co-divinylbenzene-co-N, N′-methylenediacrylamide) [Poly (NIPAAm-co-DVB-co-MBAA)] monolithic column was designed according to the chemical structures of selected TAs and used as an extraction medium engaging in hydrophobic, π-π, and hydrogen bonding interactions with analytes, allowing them to be effectively extracted. A number of important parameters were systematically optimized to achieve maximal extraction efficiency. The ion intensity of the TAs signals obtained by in-tube SPME-MS were higher than the direct MS mode by about 400 folds with the signal-to-noise ratio improved by 2–7 folds. The detection limits of the six TAs were determined as 1.99–4.06 ng g−1, with good linearity with correlation coefficients exceeding 0.99 obtained under optimal extraction conditions. Besides, TA recoveries in cigarette tobacco spiked at three concentration levels were in the range of 76.4–100.2%, and the corresponding RSDs (n = 5) were obtained as 4.32–7.16%. The extraction performance of the poly (NIPAAm-co-DVB-co-MBAA) monolithic column was well reproducible, with intra- or inter-day precision RSDs determined not to exceed 7.38%. Finally, no marked matrix effects were observed when the developed method was applied to the analysis of both high-abundance and trace-level TAs in practical samples, and the above technique was therefore concluded to be well suited for the detection of TAs in cigarette tobacco or other products.