A miniaturized matrix solid-phase dispersion methodology (µMSPD) for determination of β-carboline alkaloids in tobacco samples by UPLC-ESI-Q-TOF/MSE

Alkaloids play an important role in the chemical composition of tobacco, due to their effects that have led to the global consumption of this commodity. The β-carboline alkaloids present inhibitory action against the enzyme monoamine oxidase (MAO), which enhances the susceptibility to chemical dependence in smokers. There is a need for scientific studies to ensure the correct identification and quantification of these compounds in tobacco matrices. In this work, we present the development and validation of a microextraction analytical method for determination and quantification of the alkaloids harmaline, harmalol, harmane, harmine, norharmane, and tetrahydroharmine in natural and processed samples of tobacco, employing micro-matrix solid-phase dispersion (μMSPD), ultra-performance liquid chromatography (UPLC), and mass spectrometry (MS). The optimized μMSPD procedure employed of 0.01 g of sample, 0.1 g of Discovery® DPA-6S adsorbent, and elution with 2 mL of aqueous 1 % formic acid solution, resulting in a fast, practical, economical, and environmentally friendly technique. Validation of the methodology showed that it presented good linearity (R2 > 0.9945), satisfactory accuracy and precision (in the range from 72 ± 16 % to 109 ± 9 %), and limits of quantification (LOQ) and detection (LOD) in the ranges 0.02-1.0 µg g-1 and 0.01-0.2 µg g-1, respectively. The developed method was applied to tobacco samples, proving to be efficient for determination of β-carboline alkaloids. The compounds harmane and norharmane were quantified in samples of fresh tobacco leaves, cured tobacco leaves, twisted tobacco, and cigarettes. Harmine was only not quantified in the cigarettes.