Examinando por Autor "Vera Baquero, Fernando Leonardo"

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Chiral HPLC-MS/MS determination of hyoscyamine enantiomers in baby herbal infusions after preconcentration with sulfonic HMS mesostructured silica synthesized by co-condensation
(ELSEVIER, 2024-02-13) Vera Baquero, Fernando Leonardo; Gañán Aceituno, Judith; Morante Zarcero, Sonia; Sierra Alonso, Isabel
Tropane alkaloids are considered a major food safety issue in recent years, due to their worrying appearance in many foods, such as herbal infusions, usually due to cross-contamination with weeds during harvest. (−)-Hyoscyamine is synthesized by tropane alkaloids-producing plants and its ingestion can cause all types of disorders in humans. Its enantiomerization occurs easily over time, so the inactive (+)-hyoscyamine can be found in foods in variable proportions. Therefore, the goal of the current work was to develop a chiral high performance liquid chromatography tandem mass spectrometry method for the enantiomeric determination of (−)- and (+)-hyoscyamine. Chromatographic separation was optimized, and the best chiral resolution (Rs = 1.59) was achieved in 6.5 min with a Chiralpak® AY-3 polysaccharide-based stationary phase column using ethanol with 0.05 % diethylamine as mobile phase. For the preconcentration of the sample, two types of mesostructured silicas with sulfonic groups were synthesized, by grafting and co-condensation methods, and characterized. The materials were evaluated as sorbents for strong-cation exchange solid-phase extraction of hyoscyamine in baby herbal infusions. Based on the findings gathered, silica denoted as HMS-SO3−(co) was the best sorbent due to the high number of functional groups attached to silica (2.63 mmol/g) and its textural properties. Under optimal conditions, the preconcentration factor obtained was 167, using only 50 mg of the material, and a very low racemization of the (−)-hyoscyamine to the (+) enantiomer was found (<20 %). The method was validated with recoveries of 94–99 %, good linearity (R2 > 0.99), precision (RSD < 20 %), no matrix effect for both analytes and low method quantification limit (0.089 µg/L and 0.092 µg/L for (+)-hyoscyamine and (−)-hyoscyamine, respectively) to meet its applicability in monitoring real samples. Two types of herbal teas for babies (instant and teabags) were analyzed with the developed methodology. Two of the instantaneous infusions analysed were contaminated, one of them with 0.21 µg/L of (−)-hyoscyamine and 0.09 µg/L of (+)-hyoscyamine (ratio 70(−)/30(+)) and the other with 0.075 µg/L of (−)-hyoscyamine (the (+)- enantiomer was below the limit of quantification of the method). Taking these results into account, it is important to evaluate the content of hyoscyamine enantiomers in the infusions to avoid overestimation of (−)-hyoscyamine exposure.
Exploring Adsorption Performance of Functionalized Mesoporous Silicas with a Different Pore Structure as Strong Cation-Exchange Sorbents for Solid-Phase Extraction of Atropine and Scopolamine
(MDPI, 2025-01-10) Vera Baquero, Fernando Leonardo; Morante Zarcero, Sonia; Pérez Quintanilla, Damián; Sierra , Isabel
In this work, mesoporous silicas with two types of mesoporous structures were synthesized and functionalized with sulfonic acid groups: MCM-41-SO3H (honeycomblike hexagonal structure) and MSU-2-SO3H (three-dimensional porous structure with wormhole pores). The synthesized materials were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, nitrogen adsorption–desorption, Fourier-transform infrared spectroscopy, 29Si solid-state nuclear magnetic resonance spectroscopy, and elemental analysis. The obtained functionalized materials were evaluated as sorbents for strong cation-exchange solid-phase extraction (SPE) to determine their efficiency in the adsorption and desorption of tropane alkaloids (atropine and scopolamine). The loading solvents, loading volume, analyte concentration, and elution volume were studied, using 50 mg of both materials. Analyses were carried out by ultra-high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry. The synthesized MCM-41-SO3H material presented the highest recovery efficiency and has proven to be a promising sorbent for strong cation-exchange SPE of atropine and scopolamine in aqueous media. The high degree of functionalization of MCM-41-SO3H and the high accessibility of the sulfonic groups for the target analytes, due to the regularity and uniformity of their pores, maximize the contact between the alkaloids and the sorbent, favoring efficient adsorption.