Desarrollo de método para la determinación de componentes mayoritarios en digeridos de roca mediante electroforesis capilar con detección indirecta UV-visible

Los objetivos de la presente tesina son: • Formular un medio de separación (BGE) adecuado para la separación y cuantificación de ciertos iones inorgánicos (Na+, K+, Ca+2, Mg+2, Mn+2, Fe+3, Al+3) mediante electroforesis capilar en zonas utilizando detección indirecta UV-Vis, en condiciones de elevada fuerza iónica. • Aplicar el medio separativo formulado sobre analitos de interés geológico. Centrándose en los denominados como mayoritarios en tales muestras. • Desarrollar un método para compatibilizar las condiciones químicas de las muestras geológicas digeridas con las condiciones requeridas por la técnica de electroforesis capilar. • Ensayar la aplicabilidad del método desarrollado para analizar muestras reales de origen geológico, centrándose en la cuantificación de los iones mayoritarios que permitan la caracterización y clasificación del material geológico.Facultad de Ciencias Exacta

Desarrollo de método para la determinación de componentes mayoritarios en digeridos de roca mediante electroforesis capilar con detección indirecta UV-visible

Los objetivos de la presente tesina son: • Formular un medio de separación (BGE) adecuado para la separación y cuantificación de ciertos iones inorgánicos (Na+, K+, Ca+2, Mg+2, Mn+2, Fe+3, Al+3) mediante electroforesis capilar en zonas utilizando detección indirecta UV-Vis, en condiciones de elevada fuerza iónica. • Aplicar el medio separativo formulado sobre analitos de interés geológico. Centrándose en los denominados como mayoritarios en tales muestras. • Desarrollar un método para compatibilizar las condiciones químicas de las muestras geológicas digeridas con las condiciones requeridas por la técnica de electroforesis capilar. • Ensayar la aplicabilidad del método desarrollado para analizar muestras reales de origen geológico, centrándose en la cuantificación de los iones mayoritarios que permitan la caracterización y clasificación del material geológico.Facultad de Ciencias Exacta

Development of a background electrolyte for the determination of inorganic cations in high ionic strength samples by capillary electrophoresis with indirect UV-absorption detection

In this study, a background electrolyte capable to separate and quantify inorganic cations in high ionic strength samples by UV-absorption indirect detection was designed. In this regard, the four most abundant monovalent and divalent cations in earth crust (K+ , Na+ , Ca+2, Mg+2) were selected as model compounds. A group of small carboxylic acids and, several toluidines and pyridines were evaluated as mild strength complexing agents and chromophoric probes, respectively. The optimized background electrolyte was composed of 200 mM 2,4,6-trimethylpyridine as the chromophoric probe, 250 mM lactic acid as the weak complexing agent and pH buffering reagent (adjusted to pH 4.5), and 5 % v/v methanol as organic solvent modifier. Based on a minimum number of components, it provided outstanding separation performance in less than 4 min in a wide linear dynamic range (10 - 2500 µg∙mL-1 ). Performances were contrasted against a reference method based on conductometric detection. Furthermore, studies of separation efficiency and peak shape were carried out at different analyte concentrations in high electric conductivity solutions. The herein developed method demonstrated exceptional features in terms of limits of detection (~10 µg∙mL-1 ), resolution, speed of analysis, sensitivity and peak capacity in high electric conductivity samples. Moreover, the method was successfully applied to high ionic strength samples such as rock digest, sea water, soy sauce and isotonic drinks.Fil: Lancioni, Carlina. Universidad Nacional de la Plata. Facultad de Cs.exactas. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos. - Comision de Investigaciones Cientificas de la Provincia de Buenos Aires. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Aspromonte, Juan. Universidad Nacional de la Plata. Facultad de Cs.exactas. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos. - Comision de Investigaciones Cientificas de la Provincia de Buenos Aires. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos.; Argentina. Katholikie Universiteit Leuven; Bélgica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Tascon, Marcos. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; ArgentinaFil: Gagliardi, Leonardo Gabriel. Universidad Nacional de la Plata. Facultad de Cs.exactas. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos. - Comision de Investigaciones Cientificas de la Provincia de Buenos Aires. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin

Solid-Phase Microextraction—Gas Chromatography Analytical Strategies for Pesticide Analysis

peer reviewedDue to their extensive use and the globalized commerce of agricultural goods, pesticides have become a global concern. Despite the undoubtful advantages of their use in agricultural practices, their misuse is a threat to the environment and human health. Their analysis in environmental samples and in food products continues to gain interest in the analytical chemistry community as they are challenging matrices, and legal concentration limits are particularly low (in the order of ppb). In particular, the use of solid-phase microextraction (SPME) has gained special attention in this field thanks to its potential to minimize the matrix effect, while enriching its concentration, allowing very low limits of detection, and without the need of a large amount of solvents or lengthy procedures. Moreover, its combination with gas chromatography (GC) can be easily automated, making it a very interesting approach for routine analysis. In this review, advances and analytical strategies for the use of SPME coupled with GC are discussed and compared for the analysis of pesticides in food and environmental samples, hopefully encouraging its further development and routine application in this field

Development of a background electrolyte for the determination of inorganic cations in high ionic strength samples by capillary electrophoresis with indirect UV-absorption detection

In this study, a background electrolyte capable to separate and quantify inorganic cations in high ionic strength samples by UV-absorption indirect detection was designed. In this regard, the four most abundant monovalent and divalent cations in earth crust (K+, Na+, Ca+2, Mg+2) were selected as model compounds. A group of small carboxylic acids and, several toluidines and pyridines were evaluated as mild strength complexing agents and chromophoric probes, respectively. The optimized background electrolyte was composed of 200 mM 2,4,6-trimethylpyridine as the chromophoric probe, 250 mM lactic acid as the weak complexing agent and pH buffering reagent (adjusted to pH 4.5), and 5% v/v methanol as organic solvent modifier. Based on a minimum number of components, it provided outstanding separation performance in less than 4 min in a wide linear dynamic range (10 - 2500 µg·mL−1). Performances were contrasted against a reference method based on conductometric detection. Furthermore, studies of separation efficiency and peak shape were carried out at different analyte concentrations in high electric conductivity solutions. The herein developed method demonstrated exceptional features in terms of limits of detection (~10 µg·mL−1), resolution, speed of analysis, sensitivity and peak capacity in high electric conductivity samples. Moreover, the method was successfully applied to high ionic strength samples such as rock digest, sea water, soy sauce and isotonic drinks.Laboratorio de Investigación y Desarrollo de Métodos Analíticos (LIDMA

Exploring different high-capacity tools and extraction modes to characterize the aroma of brewed coffee

In the present work, the potential beneft of using multi-cumulative trapping headspace extraction was explored by comparing the results using solid-phase microextraction (SPME) coated with divinylbenzene/carboxen/polydimethylsiloxane and a probe-like tool coated with polydimethylsiloxane. The efciency of a single 30-min extraction, already explored in previous work, was compared with that of multiple shorter extractions. We evaluated three diferent conditions, i.e., three repeated extractions for 10 min each from diferent sample vials (for both the probe-like tool and SPME) or from the same vial (for SPME) containing brewed cofee. The entire study was performed using comprehensive two-dimensional gas chromatography coupled with mass spectrometry. The two-dimensional plots were aligned and integrated using a tile-sum approach before any statistical analysis. A detailed comparison of all the tested conditions was performed on a set of 25 targeted compounds. Although a single 30-min extraction using the probe-like tool provided a signifcantly higher compound intensity than SPME single extraction, the use of multiple shorter extractions with SPME showed similar results. However, multiple extractions with the probe-like tool showed a greater increase in the number of extracted compounds. Furthermore, an untargeted crosssample comparison was performed to evaluate the ability of the two tested tools and the diferent extraction procedures in diferentiating between espresso-brewed cofee samples obtained from capsules made of diferent packaging materials (i.e., compostable capsules, aluminum capsules, aluminum multilayer pack). The highest explained variance was obtained using the probe-like tool and multiple extractions (91.6% compared to 83.9% of the single extraction); nevertheless, SPME multiple extractions showed similar results with 88.3% of variance explained.Laboratorio de Investigación y Desarrollo de Métodos Analítico

A high throughput method for fatty acid profiling using simultaneous microwave-assisted extraction and derivatization followed by reversed fill/flush flow modulation comprehensive multidimensional gas chromatography

peer reviewe

Current Developments of Analytical Methodologies for Aflatoxins' Determination in Food during the Last Decade (2013-2022), with a Particular Focus on Nuts and Nut Products.

peer reviewedThis review aims to provide a clear overview of the most important analytical development in aflatoxins analysis during the last decade (2013-2022) with a particular focus on nuts and nuts-related products. Aflatoxins (AFs), a group of mycotoxins produced mainly by certain strains of the genus Aspergillus fungi, are known to impose a serious threat to human health. Indeed, AFs are considered carcinogenic to humans, group 1, by the International Agency for Research on Cancer (IARC). Since these toxins can be found in different food commodities, food control organizations worldwide impose maximum levels of AFs for commodities affected by this threat. Thus, they represent a cumbersome issue in terms of quality control, analytical result reliability, and economical losses. It is, therefore, mandatory for food industries to perform analysis on potentially contaminated commodities before the trade. A full perspective of the whole analytical workflow, considering each crucial step during AFs investigation, namely sampling, sample preparation, separation, and detection, will be presented to the reader, focusing on the main challenges related to the topic. A discussion will be primarily held regarding sample preparation methodologies such as partitioning, solid phase extraction (SPE), and immunoaffinity (IA) related methods. This will be followed by an overview of the leading analytical techniques for the detection of aflatoxins, in particular liquid chromatography (LC) coupled to a fluorescence detector (FLD) and/or mass spectrometry (MS). Moreover, the focus on the analytical procedure will not be specific only to traditional methodologies, such as LC, but also to new direct approaches based on imaging and the ability to detect AFs, reducing the need for sample preparation and separative techniques

Vacuum-assisted and multi-cumulative trapping in headspace solid-phase microextraction combined with comprehensive multidimensional chromatography-mass spectrometry for profiling virgin olive oil aroma

: In the present work vacuum (Vac) and multiple cumulative trapping (MCT) headspace solid phase microextraction (HS-SPME) were evaluated as alternative or combined techniques for the volatile profiling. A higher extraction performance for semi-volatiles was shown by all three techniques. Synergic combination of Vac and MCT showed up to 5-times extraction power for less volatile compounds. The hyphenation of said techniques with comprehensive two-dimensional gas chromatography (GC × GC) enabled a comprehensive analysis of the volatilome. Firstly, 18 targeted quality markers, previously defined by means of classical HS-SPME, were explored for their ability to classify commercial categories. The applicability of such markers proved to be limited with the alternative sampling techniques. An untargeted approach enables the selection of specific features for each technique showing a better classification capacity of the commercial categories. No misclassifications were observed, except for one extra virgin olive oil classified as virgin olive oil in 3 × 10 min Vac-MCT-HS-SPME

Solid-phase microextraction coupled to comprehensive multidimensional gas chromatography for food analysis.

peer reviewedSolid-phase microextraction and comprehensive multidimensional gas chromatography represent two milestone innovations that occurred in the field of separation science in the 1990s. They have a common root in their introduction and have found a perfect coupling in their evolution and applications. This review will focus on food analysis, where the paradigm has changed significantly over time, moving from a targeted analysis, focusing on a limited number of analytes at the time, to a more holistic approach for assessing quality in a larger sense. Indeed, not only some major markers or contaminants are considered, but a large variety of compounds and their possible interaction, giving rise to the field of foodomics. In order to obtain such detailed information and to answer more sophisticated questions related to food quality and authenticity, the use of SPME-GC × GC-MS has become essential for the comprehensive analysis of volatile and semi-volatile analytes. This article provides a critical review of the various applications of SPME-GC × GC in food analysis, emphasizing the crucial role this coupling plays in this field. Additionally, this review dwells on the importance of appropriate data treatment to fully harness the results obtained to draw accurate and meaningful conclusions