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1.
Anal Bioanal Chem ; 416(16): 3797-3809, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38702447

RESUMO

The increasing interest in hemp and cannabis poses new questions about the influence of drying and storage conditions on the overall aroma and cannabinoids profile of these products. Cannabis inflorescences are subjected to drying shortly after harvest and then to storage in different containers. These steps may cause a process of rapid deterioration with consequent changes in precious secondary metabolite content, negatively impacting on the product quality and potency. In this context, in this work, the investigation of the effects of freeze vs tray drying and three storage conditions on the preservation of cannabis compounds has been performed. A multi-trait approach, combining both solid-phase microextraction (SPME) two-dimensional gas chromatography coupled to mass spectrometry (SPME-GC × GC-MS) and high-performance liquid chromatography (HPLC), is presented for the first time. This approach has permitted to obtain the detailed characterisation of the whole cannabis matrix in terms of volatile compounds and cannabinoids. Moreover, multivariate statistical analyses were performed on the obtained data, helping to show that freeze drying conditions is useful to preserve cannabinoid content, preventing decarboxylation of acid cannabinoids, but leads to a loss of volatile compounds which are responsible for the cannabis aroma. Furthermore, among storage conditions, storage in glass bottle seems more beneficial for the retention of the initial VOC profile compared to open to air dry tray and closed high-density polyethylene box. However, the glass bottle storage condition causes formation of neutral cannabinoids at the expenses of the highly priced acid forms. This work will contribute to help define optimal storage conditions useful to produce highly valuable and high-quality products.


Assuntos
Canabinoides , Cannabis , Cromatografia Gasosa-Espectrometria de Massas , Microextração em Fase Sólida , Compostos Orgânicos Voláteis , Cannabis/química , Canabinoides/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Microextração em Fase Sólida/métodos , Compostos Orgânicos Voláteis/análise , Cromatografia Líquida de Alta Pressão/métodos , Inflorescência/química , Liofilização/métodos , Dessecação/métodos
2.
Molecules ; 29(4)2024 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-38398499

RESUMO

In this study, the expression and abundance of two candidate chicken (Gallus gallus; gga) microRNAs (miRNAs, miR), gga-miR-21-5p (miR-21) and gga-miR-126-5p (miR-126), have been analyzed in order to identify biomarkers for the traceability and quality of poultry meat. Two breeds of broiler chickens were tested: the most common Ross308 (fast-growing) and the high-quality Ranger Gold (slow-growing). A preliminary analysis of the two miRNAs expressions was conducted across various tissues (liver, lung, spleen, skeletal muscle, and kidney), and the three tissues (lung, spleen, and muscle) with a higher expression were chosen for further analysis. Using quantitative reverse transcription polymerase chain reaction (RT-qPCR), the expression of miRNAs in the three tissues of a total of thirteen animals was determined. The results indicate that miR-126 could be a promising biomarker for the lung tissue in the Ranger Gold (RG) breed (p < 0.01), thus suggesting a potential applicability for tracing hybrids. RG exhibits a significantly higher miR-126 expression in the lung tissue compared to the Ross308 broilers (R308), an indication of greater respiratory capacity and, consequently, a higher oxidative metabolism of the fast-growing hybrid. During sampling, two R308 broilers presented some anomalies, including airsacculitis, hepatic steatosis, and enlarged spleen. The expression of miR-126 and miR-21 was compared in healthy animals and in those presenting anomalies. Chickens with airsacculitis and hepatic steatosis showed an up-regulation of miR-21 and miR-126 in the most commercially valuable tissue, the skeletal muscle or breast (p < 0.05).


Assuntos
MicroRNAs , Animais , MicroRNAs/genética , MicroRNAs/metabolismo , Galinhas/genética , Galinhas/metabolismo , Aves Domésticas , Músculo Esquelético/metabolismo , Inocuidade dos Alimentos
3.
Anal Chem ; 95(25): 9630-9637, 2023 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-37294639

RESUMO

The retention behavior of small molecules and N-protected amino acids on a zwitterionic teicoplanin chiral stationary phase (CSP), prepared on superficially porous particles (SPPs) of 2.0 µm particle diameter, has shown that efficiency and enantioselectivity, and so enantioresolution, dramatically change depending on the employed organic modifier. In particular, it was found that while methanol permits the boost of enantioselectivity and resolution of the amino acids, at the cost of efficiency, acetonitrile allows for the ability to reach extraordinary efficiency even at high flow rates (with reduced plate height <2 and up to 300,000 plates/m at the optimum flow rate). To understand these features, an approach based on the investigation of mass transfer through the CSP, the estimation of the binding constants of amino acids on the CSP, and the assessment of compositional properties of the interfacial region between bulk mobile phase and solid surface has been adopted.

4.
Anal Bioanal Chem ; 415(18): 4545-4555, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37093233

RESUMO

Water is a fundamental resource for living things, which is why its control is necessary. The widespread use of pesticides for agricultural and non-agricultural purposes has resulted in the presence of their residues in surface water and groundwater resources. Their presence in water is regulated through different directives, such as the Groundwater Directive, the Drinking Water Directive, and the Water Framework Directive, modified later several times, setting a maximum concentration of 0.1 µg.L-1 for individual pesticides and their degradation products, and 0.5 µg.L-1 for total pesticide residues present in a sample. There are different kinds of pesticides (e.g., organophosphorus and organochlorine pesticides, triazines, chloroacetamides, triazoles, (thio)carbamates) that have diverse chemical structures. Their determination and monitoring in a single analytical procedure are possible through multiresidue methods. In this study, 53 pesticides belonging to different chemical classes and their metabolites were selected based on their local occurrence and investigated in surface water and groundwater from agricultural areas susceptible to pesticide contamination. The methodology consisted of a classical solid-phase extraction (SPE) for the purification and enrichment of the pesticides, with a subsequent analysis in multidimensional gas chromatography coupled to mass spectrometry (GC×GC-MS). The quantification method was validated according to the Eurachem Guide in terms of linearity, precision, accuracy, limit of detection, and limit of quantification. After validation, the method was applied to 34 real-world water samples, and the results were compared with those obtained by a GC-QMS routine method.


Assuntos
Resíduos de Praguicidas , Praguicidas , Poluentes Químicos da Água , Praguicidas/análise , Resíduos de Praguicidas/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Agricultura , Água/química , Extração em Fase Sólida/métodos , Poluentes Químicos da Água/análise
5.
Anal Bioanal Chem ; 415(13): 2343-2355, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36650250

RESUMO

One convenient strategy to reduce environmental impact and pollution involves the reuse and revalorization of waste produced by modern society. Nowadays, global plastic production has reached 367 million tons per year and because of their durable nature, their recycling is fundamental for the achievement of the circular economy objective. In closing the loop of plastics, advanced recycling, i.e., the breakdown of plastics into their building blocks and their transformation into valuable secondary raw materials, is a promising management option for post-consumer plastic waste. The most valuable product from advanced recycling is a fluid hydrocarbon stream (or pyrolysis oil) which represents the feedstock for further refinement and processing into new plastics. In this context, gas chromatography is currently playing an important role since it is being used to study the pyrolysis oils, as well as any organic contaminants, and it can be considered a high-resolution separation technique, able to provide the molecular composition of such complex samples. This information significantly helps to tailor the pyrolysis process to produce high-quality feedstocks. In addition, the detection of contaminants (i.e., heteroatom-containing compounds) is crucial to avoid catalytic deterioration and to implement and design further purification processes. The current review highlights the importance of molecular characterization of waste stream products, and particularly the pyrolysis oils obtained from waste plastics. An overview of relevant applications published recently will be provided, and the potential of comprehensive two-dimensional gas chromatography, which represents the natural evolution of gas chromatography into a higher-resolution technique, will be underlined.

6.
J Sep Sci ; 43(9-10): 1737-1745, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32125067

RESUMO

Three columns packed with 2.0 µm superficially porous particles, 1.7 µm fully porous particles, and monodisperse 1.9 µm fully porous particles with narrow particle size distribution have been deeply characterized from a kinetic point of view. The 1.9 µm column showed excellent kinetic performance, comparable to that of the superficially porous one. These two columns also exhibit flatter c-branches of the van Deemter curve compared to the 1.7 µm fully porous particles column, resulting in smaller loss of efficiency when they are operated at higher flow rates than the optimal ones. The independent evaluation of each contribution to band broadening has revealed that the difference in kinetic performance comes from the very small eddy dispersion contribution on the 1.9 µm column, surprisingly even lower than that of the superficially porous one. This finding suggests a very good packing of the monodisperse 1.9 µm column. On the other hand, the potential of 1.7 µm fully porous particles is completely broken down by the strong frictional heating effect already arising at relatively low flow rates.

7.
Molecules ; 25(15)2020 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-32708013

RESUMO

The present work focused on the use of high-silica commercial zeolites as sorbent media for pharmaceuticals in an aqueous matrix. As drug probes, ketoprofen, hydrochlorothiazide, and atenolol were selected, because of their occurrence in surface waters and effluents from wastewater treatment plants. Pharmaceuticals adsorption was evaluated for two Faujasite topology zeolites with Silica/Alumina Ratio 30 and 200. The selected zeolites were demonstrated to be efficient sorbents towards all investigated pharmaceuticals, thanks to their high saturation capacities (from 12 to 32% w/w) and binding constants. These results were corroborated by thermal and structural analyses, which revealed that adsorption occurred inside zeolite's porosities, causing lattice modifications. Finally, zeolites have been tested as a pre-concentration media in the dispersive-solid phase extraction procedure. Recoveries higher than 95% were gained for ketoprofen and hydrochlorothiazide and approximately 85% for atenolol, at conditions that promoted the dissolution of the neutral solute into a phase mainly organic. The results were obtained by using a short contact time (5 min) and reduced volume of extraction (500 µL), without halogenated solvents. These appealing features make the proposed procedure a cost and time saving method for sample enrichment as well as for the regeneration of exhausted sorbent, rather than the more energetically expensive thermal treatment.


Assuntos
Dióxido de Silício/química , Zeolitas/química , Adsorção , Atenolol/química , Hidroclorotiazida/química , Cetoprofeno/química , Porosidade , Extração em Fase Sólida , Solventes/química , Propriedades de Superfície , Água , Poluentes Químicos da Água/química
8.
Photochem Photobiol Sci ; 18(9): 2150-2163, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-30931455

RESUMO

WO3/BiVO4 films obtained by electrochemical deposition of BiVO4 over mesoporous WO3 were applied to the photoelectrochemical degradation of selected emerging contaminants (ketoprofen and levofloxacine) in aqueous solutions. The WO3/BiVO4 films in this work are characterized by a mesoporous morphology with a maximum photoconversion efficiency >40% extending beyond 500 nm in Na2SO4 electrolytes. Oxygen was found to be the dominant water oxidation product (ca. 90% faradaic yield) and no evidence for the photogeneration of OH radicals was obtained. Nevertheless, both 10 ppm levofloxacine and ketoprofen could be degraded at WO3/BiVO4 junctions upon a few hours of illumination under visible light. However, while levofloxacine degradation intermediates were progressively consumed by further oxidation at the WO3/BiVO4 interface, ketoprofen oxidation byproducts, being stable aromatic species, were found to be persistent in aqueous solution even after 15 hours of solar simulated illumination. This indicates that, due to the lower oxidizing power of photogenerated holes in BiVO4 and a different water oxidation mechanism, the employment of WO3/BiVO4 in photoelectrochemical environmental remediation processes is much less universal than that possible with wider band gap semiconductors such as TiO2 and WO3.

9.
Anal Chem ; 90(18): 10828-10836, 2018 09 18.
Artigo em Inglês | MEDLINE | ID: mdl-30133261

RESUMO

This proof-of-concept work investigates the ultimate kinetic limits reachable in chiral supercritical fluid chromatography (SFC) with modern columns and advanced technological solutions. A commercial equipment (Waters Acquity UPC2) has been in-house modified to minimize its overall extra-column variance through a series of technical adjustments including low-volume connecting tubings, reduced-volume flow cell, an in-house made external column oven, external low-dispersion injection system, and electronic temperature controller. Compared to the original (as-shipped) configuration, the extra-column variance on the low-dispersion equipment was reduced by more than 97%, from about 85 to slightly more than 2 µL2 (measured at 2.0 mL/min). This was mainly achieved thanks to the occurrence of fully developed turbulent regime with a proper selection of capillary i.d. at significantly smaller flow rates (1.5-4 mL/min; CO2/methanol 80/20, v/v; 35 °C; back pressure regulator (BPR), 105 bar) than in entry-1 configuration. Ultrahigh efficiency columns of different geometries in-house packed with latest generation sub-2 µm UHPC-FPP-Whelk-O1 Chiral Stationary Phase (CSP) have been employed under sub- and supercritical fluid conditions. By carefully modulating the length and the internal diameter of connecting tubings in the function of column geometry, state of the art efficiencies (estimated in roughly 300 000 theoretical plates/m with reduced HETP of roughly 1.85) have been obtained on 4.6 mm i.d. chiral columns. Remarkably, for 3.0 mm × 100 mm (i.d. × length) columns, the efficiency gain on the fully modified SFC system (compared to an instrumental configuration where only the standard injector was replaced by the low-dispersion one) was greater than 90% for compounds with a retention factor of 1 and as large as 25% for retention factors of 2.5.

10.
Chemphyschem ; 19(17): 2208-2217, 2018 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-29774636

RESUMO

The adsorption behavior of neodymium (Nd3+ ) and yttrium (Y3+ ) cations on synthetic FAU zeolite X in its sodium form (NaX) has been investigated by means of macroscopic (adsorption isotherm determination and thermal analysis) and microscopic measurements (including solid-state NMR spectroscopy and X-ray powder diffraction). The multidisciplinary study reveals some unexpected features. Firstly, adsorption constants of cations are not correlated to their ionic radii or hydration enthalpy. The adsorption constant of Y3+ on NaX was indeed about twice that of Nd3+ , which is the opposite of what could be expected based on the size of the cations. In addition, adsorption was accompanied by partial dealumination of the zeolite framework. The extent of dealumination changed depending on the exchanged cations, with the extent being more significant on the Nd-exchanged zeolite than on the Y-exchanged one. The most interesting finding of this study, however, is the presence of supramolecular clusters composed of water, Nd3+ , residual sodium ions, and extra-framework aluminum at the interface of Nd-exchanged zeolite. The hypothesis that these host-guest complexes are responsible of the significantly different behavior exhibited by NaX towards the adsorption/desorption of Nd3+ and Y3+ has been formulated.

11.
Anal Bioanal Chem ; 410(10): 2457-2465, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29340722

RESUMO

About ten years after their introduction to the market (happened in 2006), the so-called second generation superficially porous particles (SPPs) have undoubtedly become the benchmark as well as, very often, the preferred choice for many applications in liquid chromatography (LC), when high efficiency and fast separations are required. This trend has interested practically all kinds of separations, with the only exception of chiral chromatography (at least so far). The technology of production of base SPPs is advanced, relatively simple and widely available. The deep investigation of mass transfer mechanisms under reversed-phase (RP) and normal-phase (NP) conditions for achiral separations has shown the advantages in the use of these particles over their fully porous counterparts. In addition, it has been demonstrated that SPPs are extremely suitable for the preparation of efficient packed beds through slurry packing techniques. However, the research in this field is in continual evolution. In this article, some of the most advanced concepts and modern applications based on the use of SPPs, embracing in particular ultrafast chiral chromatography and the design of SPPs with engineered pore structures or very reduced particle diameter, are revised. We describe modern trends in these fields and focus on those aspect where further innovation and research will be required. Graphical Abstract Word cloud of cutting edge applications of superficially porous particles in liquid chromatography.

12.
Molecules ; 23(10)2018 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-30347852

RESUMO

Until less than 10 years ago, chiral separations were carried out with columns packed with 5 or 3 µ m fully porous particles (FPPs). Times to resolve enantiomeric mixtures were easily larger than 30 min, or so. Pushed especially by stringent requirements from medicinal and pharmaceutical industries, during the last years the field of chiral separations by liquid chromatography has undergone what can be defined a "true revolution". With the purpose of developing ever faster and efficient method of separations, indeed, very efficient particle formats, such as superficially porous particles (SPPs) or.


Assuntos
Cromatografia Líquida , Cromatografia com Fluido Supercrítico , Compostos Fitoquímicos/isolamento & purificação , Extratos Vegetais/química , Humanos , Cinética , Compostos Fitoquímicos/química , Compostos Fitoquímicos/uso terapêutico , Extratos Vegetais/uso terapêutico , Porosidade , Estereoisomerismo
13.
Analyst ; 142(4): 555-566, 2017 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-28091634

RESUMO

This review focuses on the use of superficially porous particles (SPPs) as chiral stationary phases for ultra-high performance liquid enantioseparations. In contrast to what happened in achiral separations where core-shell particles invaded the market, the introduction of SPPs in chiral liquid chromatography (LC) has been relatively recent. This is due in part to the technical difficulties in the preparation of these phases, and in part to scarce understanding of mass transfer phenomena in chiral chromatography. As a matter of fact, nowadays, the development of superficially porous CSPs is still in its infancy. This paper covers the most recent advancements in the field of core-shell technology applied to chiral separations. We review the kinds of chiral selectors that have been used for the preparation of these phases, by discussing the advantages of chiral SPPs over their fully-porous counterparts for high efficient high throughput enantioseparations. Notwithstanding the apparently obvious advantages in terms of the mass transfer of chiral SPPs, some critical aspects that could impact their development are presented.

14.
Anal Chem ; 87(13): 6854-60, 2015 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-26047527

RESUMO

Terms such as "fluorous affinity" and "fluorophilicity" have been used to describe the unique partition and sorption properties often exhibited by highly fluorinated organic compounds, that is molecules rich in sp(3) carbon-fluorine bonds. In this work, we made use of a highly fluorinated stationary phase and a series of benzene derivatives to study the effect of one single perfluorinated carbon on the chromatographic behavior and adsorption properties of molecules. For this purpose, the adsorption equilibria of α,α,α-trifluorotoluene, toluene, and other alkylbenzenes have been studied by means of nonlinear chromatography in a variety of acetonitrile/water eluents. Our results reveal that one single perfluorinated carbon is already enough to induce a drastic change in the adsorption properties of molecules on the perfluorinated stationary phase. In particular, it has been found that adsorption is monolayer if the perfluoroalkyl carbon is present but that, when this unit is missing, molecules arrange as multilayer stack structures. These findings can contribute to the understanding of molecular mechanisms of fluorous affinity.


Assuntos
Cromatografia de Afinidade/métodos , Flúor/química , Adsorção
15.
Anal Bioanal Chem ; 407(1): 17-21, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25358910

RESUMO

Perfluorinated (F-) adsorbents are generally prepared by bonding perfluoro-functionalized silanes to silica gels. They have been employed for a long time essentially as media for solid-phase extraction of F-molecules or F-tagged molecules in organic chemistry and heterogeneous catalysis. More recently, this approach has been extended to proteomics and metabolomics. Owing to their unique physicochemical properties, namely fluorophilicity and proteinophilicity, and a better understanding of some fundamental aspects of their behavior, new applications of F-adsorbents in the field of environmental science and bio-affinity studies can be envisaged. In this article, we revisit the most important features of F-adsorbents by focusing, in particular, on some basic information that has been recently obtained through (nonlinear) chromatographic studies. Finally, we try to envisage new applications and possibilities that F-adsorbents will allow in the near future.


Assuntos
Cromatografia Líquida de Alta Pressão/instrumentação , Compostos de Flúor/química , Extração em Fase Sólida/instrumentação , Adsorção , Animais , Humanos , Proteômica/instrumentação
16.
Anal Bioanal Chem ; 407(18): 5405-15, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25956598

RESUMO

We present a capillary electrophoresis method for determining two different C8-conjugated deoxyadenosines, and for oligonucleotides containing them, in which a psoralen or an acridine molecule is bonded to the base via a short alkyl chain containing sulfur ethers at both ends. The sensitivity of the micellar electrokinetic chromatography (MEKC) method was increased by using two preconcentration techniques, micro solid-phase extraction (µSPE) followed by reversed-electrode-polarity stacking mode (REPSM). Variables that affect the efficiency of the extraction in µSPE and preconcentration by REPSM, including the type and volume of extraction nanoparticle, concentration, and injection time, were investigated. Under the optimum conditions, enrichment factors obtained were in the range 360-400. The limits of detection (LODs) at a signal-to-noise ratio of 3 ranged from 2 to 5 nmol L(-1). The relative recoveries of labelled adenosines from water samples were 95-103%. The proposed method provided high enrichment factors and good precision and accuracy with a short analysis time. On the basis of the advantages of simplicity, high selectivity, high sensitivity, and good reproducibility, the proposed method may have great potential for biochemical applications.


Assuntos
Desoxiadenosinas/análise , Eletroforese Capilar/métodos , Ouro/química , Nanopartículas Metálicas/química , Oligonucleotídeos/análise , Sulfetos/análise , Adenosina/análise , Adenosina/urina , Adulto , Cromatografia Capilar Eletrocinética Micelar/instrumentação , Cromatografia Capilar Eletrocinética Micelar/métodos , Desoxiadenosinas/urina , Eletrodos , Eletroforese Capilar/instrumentação , Desenho de Equipamento , Feminino , Humanos , Limite de Detecção , Nanopartículas Metálicas/ultraestrutura , Oligonucleotídeos/urina , Reprodutibilidade dos Testes , Sulfetos/urina
17.
Anal Chem ; 86(10): 4919-26, 2014 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-24725093

RESUMO

The chromatographic retention mechanisms of two hydrophobic bonded phases, octadecyl ethyl-bridged organic/inorganic (BEH-C18) and straight-chain perfluorohexylpropyl silica (C6F13), have been investigated by using a homologous series of alkyl-benzenes and perfluoroalkyl acids as test compounds in a variety of acetonitrile/water mobile phases and at different temperatures. On both columns, polar compounds exhibited a characteristic U-shape retention behavior in function of acetonitrile amount in the eluent, whereas retention of neutral molecules decreased continuously, following an increase of organic modifier, over the entire mobile phase range. The dependence of perfluoromethylene selectivity upon eluent composition explains the typical reversed-phase behavior (decreasing in retention following an increase of acetonitrile in mobile phase) initially exhibited by perfluoroalkyl acids, but alone it cannot justify their increasing of retention at organic-rich mobile phases (approximately >90% v/v for acetonitrile with the C6F13 column and acetonitrile >80% v/v for the BEH-C18 one). It actually predicts an opposite trend, indicating thus the presence of mixed-mode retention mechanisms. Indeed it was found that, at organic-rich mobile phases, the transfer from the mobile to the stationary phase of the polar moiety of molecules drives retention. This finding has been correlated to the excess adsorption isotherm of acetonitrile/water binary mixtures and thus to the composition of the stationary phase. At organic-rich mobile phases, in fact, stationary phases are characterized by a positive excess of adsorbed water that creates an "environment" suitable to the transfer herein of polar groups.

18.
Chemistry ; 20(26): 8138-48, 2014 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-24890919

RESUMO

The structural and chromatographic characterization of two novel fluorinated mesoporous materials prepared by covalent reaction of 3-(pentafluorophenyl)propyldimethylchlorosilane and perfluorohexylethyltrichlorosilane with 2.5 µm fully porous silica particles is reported. The adsorbents were characterized by solid state (29)Si, (13)C, and (19)F NMR spectroscopy, low-temperature nitrogen adsorption, elemental analysis (C and F), and various chromatographic measurements, including the determination of adsorption isotherms. The structure and abundance of the different organic surface species, as well as the different silanol types, were determined. In particular, the degree of so-called horizontal polymerization, that is, Si-O-Si bridging parallel to the silica surface due to the reaction, under "quasi-dry" conditions, of trifunctional silanizing agents with the silica surface was quantified. Significant agreement was found between the information provided by solid-state NMR, elemental analysis, and excess isotherms regarding the amount of surface residual silanol groups, on the one hand, and the degree of surface functionalization, on the other. Finally, the kinetic performance of the fluorinated materials as separation media for applications in near-ultrahigh-performance liquid chromatography was evaluated. At reduced velocities of about 5.5 (ca. 600 bar backpressure at room temperature) with 3 mm diameter columns and toluene as test compound, reduced plate heights on the order of 2 were obtained on columns of both adsorbents.


Assuntos
Cromatografia Líquida/métodos , Espectroscopia de Ressonância Magnética/métodos , Dióxido de Silício/química , Adsorção , Halogenação
19.
J Agric Food Chem ; 72(37): 20670-20678, 2024 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-39230505

RESUMO

Aflatoxins pose a major health concern and require strict monitoring in food products. Existing methods rely on hazardous organic solvents for extraction, prompting the development of a greener alternative. This study explores deep eutectic solvents (DESs) for aflatoxin extraction from pistachios, a valuable food product prone to aflatoxin contamination. The proposed method utilizes DES extraction followed by solid-phase extraction cleanup and ultrahigh-performance liquid chromatography coupled with fluorescence detector analysis. Recovery rates ranged from 85.5 to 99.1% for pistachios spiked with 1-8 ng/g aflatoxins, in compliance with EU regulations, with coefficients of variation less than 2.94%. The method demonstrates good sensitivity with limits of detection and quantification in the range of 0.02-0.22 ng/g and 0.05-0.72 ng/g, respectively. Greenness assessment using AGREEPrep and White Analytical Chemistry metrics confirms its environmental sustainability. This approach offers a promising, safer, and more eco-friendly alternative for aflatoxin extraction from complex food matrices like pistachios.


Assuntos
Aflatoxinas , Solventes Eutéticos Profundos , Contaminação de Alimentos , Extração em Fase Sólida , Aflatoxinas/análise , Aflatoxinas/isolamento & purificação , Cromatografia Líquida de Alta Pressão/métodos , Contaminação de Alimentos/análise , Extração em Fase Sólida/métodos , Extração em Fase Sólida/instrumentação , Solventes Eutéticos Profundos/química , Nozes/química
20.
Food Chem ; 460(Pt 3): 140702, 2024 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-39116768

RESUMO

An optimized procedure for extracting and analyzing raw pistachio volatiles was developed through headspace sampling with high-capacity tools and subsequent analysis using comprehensive two-dimensional gas chromatography coupled with mass spectrometry. The examination of 18 pistachio samples belonging to different geographic areas led to the identification of a set of 99 volatile organic compounds (VOCs). Molecules were putatively identified using linear retention index, mass spectra similarity, and two-dimensional plot location. The impact of preprocessing and processing techniques on the aligned data matrix from a set of samples of different geographical origins, after removing contaminants, was evaluated. The combination of scaling with log-transformation, normalization with z-score, and data reduction with random forest machine learning algorithm generated a panel of 16 discriminatory VOC molecules. As a proof of concept, raw pistachios' VOC profile was employed for the first time to tentatively classify them based on their geographical origin.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas , Pistacia , Compostos Orgânicos Voláteis , Compostos Orgânicos Voláteis/química , Compostos Orgânicos Voláteis/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Pistacia/química , Pistacia/classificação , Geografia , Estudo de Prova de Conceito
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