A miniaturized matrix solid-phase dispersion methodology (µMSPD) for determination of ß-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 ß-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 ß-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.

Use of Magnesium Silicate as a New Type of Adsorbent for Dispersive Solid-Phase Extraction Cleanup of the Quick, Cheap, Effective, Rugged, and Safe Method for Pesticides During Analysis of Lager Beer by Gas Chromatography-Tandem Mass Spectrometry.

Background: Pesticides are applied for pest control during the production of cereal grains used in beer production. Given the risks for consumers, it is important to analyze the pesticide residues. Objective: Quick, easy, cheap, effective, rugged, and safe (QuEChERS)-based methods are very effective, and improvement in the cleanup step is an important approach. Methods: Primary secondary amine (PSA) and magnesium silicate were evaluated for dispersive-solid-phase extraction (d-SPE) cleanup step in extracts provided by the QuEChERS method in combination with GC-tandem MS for the determination of acetamiprid, terburfos, alachlor, ametryn, atrazine, azoxystrobin, carbofuran, carbosulfan, cypermethrin, deltamethrin, difenoconazole, esfenvalerate, flutriafol, thiamethoxam, and parathion-methyl in lager beer. Results: The amount of 50 mg of magnesium silicate was suitable for cleaning up beer extract as an alternative d-SPE material to PSA. The method was validated using beer fortified with pesticides at three concentration levels (0.002, 0.01, and 0.1 µg/mL). Average recoveries ranged from 70 to 123%, with RSDs between 0.3 and 10.5 %. Matrix effects were observed by comparing the slope of matrix-matched standard calibration with that of solvent. The method provided good linearity at the concentration levels of 0.001-2.5 µg/mL. Detection limits ranged from 0.0001 to 0.0007 µg/mL and quantification limits ranged from 0.001 to 0.006 µg/mL. The method was applied to nine beer brands. Conclusions: Results showed that magnesium silicate is an efficient alternative cleanup material to reduce analysis costs while maintaining the method reliability and accuracy. Highlights: Magnesium silicate was effective as adsorbent for d-SPE step in the analysis of pesticides in beer.

MSPD sample preparation approach for reversed-phase liquid chromatographic analysis of pesticide residues in stem of coconut palm.

A method was developed using matrix solid-phase dispersion, together with liquid chromatography with ultraviolet diode array detector for determination of carbofuran, difenoconazole, ß-cyfluthrin, spirodiclofen and thiophanate-methyl in stem of coconut palm. The best results were obtained using 2.0 g of stem, 1.6 g of Florisil as sorbent and cyclohexane:acetone mixture (4:1). The method was validated using stem samples spiked with pesticides at four concentration levels (0.05-2.0 µg/g). Average recoveries ranged from 70 % to 114.3 %, with relative standard deviations between 1.2 % and 19.2 %. Detection and quantification limits were in the ranges 0.02-0.03 and 0.05-0.1 µg/g, respectively.