On-line solid-phase extraction for liquid chromatography-mass spectrometry analysis of pesticides

Public concern about pesticides in food and water has increased dramatically in the last two decades. In order to guarantee consumers' health and safety, analytical methods that could provide fast and reliable answers without compromising accuracy and precision are required. Sample treatment is probably the most tedious and time-consuming step in many analytical procedures and, despite the significant advances in chromatographic separations and mass spectrometry techniques, sample treatment is still one of the most important parts of the analytical process for achieving good analytical results. Therefore, over the last years, considerable efforts have been made to simplify the stage and to develop fast, accurate and robust methods which allow the determination of a wide range of pesticides without compromising the integrity of the extraction process. This review article intends to give a short overview of recently developed on-line solid-phase extraction, pre-concentration and clean-up procedures for the determination of pesticides in complex matrices by liquid chromatography-mass spectrometry techniques

Liquid Chromatography-High-resolution Mass Spectrometry (LC-HRMS) Fingerprinting and Chemometrics for Coffee Classification and Authentication

Nowadays, the quality of natural products is an issue of great interest in our society due to the increase in adulteration cases in recent decades. Coffee, one of the most popular beverages worldwide, is a food product easily adulterated. To prevent fraudulent practices, it is necessary to develop feasible methodologies to authenticate and guarantee not only the coffee origin but also its variety, as well as its roasting degree. In the present study, a C18 reversed-phase liquid chromatography (LC) technique coupled to high-resolution mass spectrometry (HRMS) was applied to address the characterization and classification of Arabica and Robusta coffee samples from different production regions using chemometrics. The proposed non-targeted LC-HRMS method using electrospray ionization in negative mode was applied to the analysis of 306 coffee samples belonging to different groups depending on the variety (Arabica and Robusta), the growing region (e.g., Ethiopia, Colombia, Nicaragua, Indonesia, India, Uganda, Brazil, Cambodia and Vietnam), and the roasting degree. Analytes were recovered with hot water as the extracting solvent (coffee brewing). The data obtained was considered the source of potential descriptors to be exploited for the characterization and classification of the samples using principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA). Besides, different adulteration cases, involving nearby production regions and different varieties, were evaluated by pairs (e.g., Vietnam Arabica – Vietnam Robusta, Vietnam Arabica – Cambodia and Vietnam Robusta – Cambodia). The coffee adulteration studies carried out by partial least squares (PLS) regression demonstrated the good capability of the proposed methodology to quantify adulterant levels down to 15%, accomplishing calibration and prediction errors below 2.7% and 11.6%, respectively

Non-targeted HPLC-FLD fingerprinting for the detection and quantitation of adulterated coffee samples by chemometrics

Coffee is today one of the most popular beverages in the world and the determination of its authenticity is an important issue considering the increase of adulteration cases in the last years. In this work, a simple and efficient non-targeted HPLC-FLD fingerprinting method was employed to detect and quantify adulteration levels in coffee samples by partial least squares (PLS) regression to guarantee food integrity and authenticity. For that purpose, different adulteration cases, involving both coffee production region and variety, were evaluated by pairs (Colombia-Ethiopia, Colombia-Nicaragua, India-Indonesia, Vietnam Arabica-Vietnam Robusta, Vietnam Arabica-Cambodia, and Vietnam Robusta-Cambodia adulteration cases). Overall, the proposed non-targeted HPLC-FLD fingerprinting strategy showed very good results with PLS cross-validation and prediction errors below 3.4% and 7.5%, respectively, for adulteration levels below 15%. Therefore, non-targeted HPLC-FLD fingerprints demonstrated to be suitable to assess coffee integrity and authenticity in the control and prevention of frauds

Authenticity assessment and fraud quantitation of coffee adulterated with chicory, barley and blours by untargeted HPLC-UV-FLD fingerprinting and chemometrics

Coffee, one of the most popular drinks around the world, is also one of the beverages most sus-ceptible of being adulterated. Untargeted high-performance liquid chromatography with ultra-violet and fluorescence detection (HPLC-UV-FLD) fingerprinting strategies in combination with chemometrics were employed for the authenticity assessment and fraud quantitation of adulter-ated coffees involving three different and common adulterants: chicory, barley and flours. The methodologies were applied after a solid-liquid extraction procedure with a methanol:water 50:50 (v/v) solution as extracting solvent. Chromatographic fingerprints were obtained using a Kinetex® C18 reversed-phase column under gradient elution conditions using 0.1% formic acid aqueous solution and methanol as mobile phase components. The obtained coffee and adulter-ants extract HPLC-UV-FLD fingerprints were evaluated by partial least squares regres-sion-discriminants analysis (PLS-DA) resulting to be excellent chemical descriptors for sample discrimination. 100% classification rates for both PLS-DA calibration and prediction models were obtained. Besides, Arabica and Robusta coffee samples were adulterated with chicory, bar-ley and flours, and the obtained HPLC-UV-FLD fingerprints subjected to partial least squares (PLS) regression, demonstrating the feasibility of the proposed methodologies to assess coffee authenticity and to quantify adulteration levels (down to 15%), showing both calibration and prediction errors below 1.3% and 2.4%, respectively

Editorial for the Special Issue, 'Chemistry of Essential Oils and Food Flavours'

Essential oils have important functions in nature. In addition, they are used commercially as in areas such as flavours, fragrances and health-care products. Their properties present a challenge with respect to investigating their chemical composition, function, bioactivity, analysis and commercialization as val-ue-added products. Analytical techniques for the investigation of essential oil chemistry are continuously evolving. The sophistication, adulteration or imitation of natural products is becoming difficult to detect as the perpetrators also use modern techniques. Consequently, an understanding of the chemistry of essential oils that keeps abreast with the latest in instrumental and computational developments is paramount. Thus, the objective of this Special Issue is to broadcast some of the latest advances in essential oil discoveries with respect to oil chemistry, methodology, instrumentation, bio-activity, chemical ecology, biosynthesis and authentication especially in relation to foods. This Special Issue will be useful for all readers in terms of the novel information it provides on the chemistry of essential oils and food flavors

Caracterización y determinación de sales de amonio cuaternario por técnicas cromatográficas, electroforéticas y espectrometría de masas

El objetivo de la presente tesis ha sido el desarrollo de metodología analítica para la determinación y caracterización de dos familias de sales de amonio cuaternario. La primera se conoce genéricamente con el nombre de quats y son compuestos que se utilizan como herbicidas y reguladores del crecimiento vegetal. La segunda familia objeto de estudio es un grupo de sales de amonio cuaternario con carácter biocida donde se han incluido los diferentes homólogos del cloruro de bensalconio y el cloruro de didecildimetilamonio. Con respecto a la familia de los quats, se han desarrollado métodos de preconcentración on-line en electroforesis capilar para su determinación, basados en los fenómenos de "stacking" y "sweeping". También se ha estudiado el acoplamiento de la electroforesis capilar a la espectrometría de masas utilizando un analizador de trampa de iones y una fuente de ionización de electropulverización. Los métodos desarrollados basados en técnicas electroforéticas han permitido en todos los casos analizar los quats en muestras de agua de bebida a los niveles legislados por la Agencia de Protección del Medio Ambiente de los EE.UU (US EPA) y, en algunos casos, a los niveles requeridos también por la Unión Europea. También se ha automatizado un método de preconcentración on-line utilizando un sistema de preconcentración Prospeckt y se ha acoplado a métodos LC-MS utilizando analizadores de triple cuadrupolo y de tiempo de vuelo. Los resultados obtenidos para la determinación de los quats con el triple cuadrupolo han resultado ser los mejores entre los descritos hasta el momento para estos compuestos

Caracterización y determinación de sales de amonio cuaternario por técnicas cromatográficas, electroforéticas y espectrometría de masas

[spa] El objetivo de la presente tesis ha sido el desarrollo de metodología analítica para la determinación y caracterización de dos familias de sales de amonio cuaternario. La primera se conoce genéricamente con el nombre de quats y son compuestos que se utilizan como herbicidas y reguladores del crecimiento vegetal. La segunda familia objeto de estudio es un grupo de sales de amonio cuaternario con carácter biocida donde se han incluido los diferentes homólogos del cloruro de bensalconio y el cloruro de didecildimetilamonio. Con respecto a la familia de los quats, se han desarrollado métodos de preconcentración on-line en electroforesis capilar para su determinación, basados en los fenómenos de "stacking" y "sweeping". También se ha estudiado el acoplamiento de la electroforesis capilar a la espectrometría de masas utilizando un analizador de trampa de iones y una fuente de ionización de electropulverización. Los métodos desarrollados basados en técnicas electroforéticas han permitido en todos los casos analizar los quats en muestras de agua de bebida a los niveles legislados por la Agencia de Protección del Medio Ambiente de los EE.UU (US EPA) y, en algunos casos, a los niveles requeridos también por la Unión Europea. También se ha automatizado un método de preconcentración on-line utilizando un sistema de preconcentración Prospeckt y se ha acoplado a métodos LC-MS utilizando analizadores de triple cuadrupolo y de tiempo de vuelo. Los resultados obtenidos para la determinación de los quats con el triple cuadrupolo han resultado ser los mejores entre los descritos hasta el momento para estos compuestos

Liquid chromatographic fingerprints for the characterization of flavanol-rich nutraceuticals based on 4-dimethylaminocinnamaldehyde precolumn derivatization

Flavanols consist of a great family of bioactive molecules displaying a wide range of health-promoting attributes for humans, including antioxidant, antimicrobial or an-ti-inflammatory effects. As a result, botanical species rich in this type of compounds are often used to develop nutraceutical products or dietary supplements with recognized healthy attrib-utes. This paper aims at characterizing nutraceutical products using liquid chromatographic fin-gerprints related to flavanol composition. Catechins and their oligomers were exploited to characterize and authenticate of various commercial products prepared with extracts of red ber-ries and medicinal plants. These compounds resulted in interesting descriptors of some fruits and vegetables, thus providing an additional perspective for the study of nutraceuticals. For such a purpose, a new method based on liquid chromatography with UV/Vis detection (HPLC-UV/Vis) with precolumn derivatization with 4-dimethylaminocinnamaldehyde was de-veloped. Results indicated that the separation of flavanols was very complex due to the degrada-tion of procyanidin derivatives. The resulting data sets were analyzed using chemometric methods such as principal component analysis and partial least square-discriminant analysis. Despite the complexity of chromatographic fingerprints, nutraceutical samples could be dis-criminated according to their main ingredients. In general, catechin and epicatechin were the most abundant compounds in the different samples and procyanidin A2 was highly specific of cranberry

Field-Amplified Sample Injection-Micellar Electrokinetic Chromatography for the Determination of Benzophenones in Food Simulants

A field-amplified sample injection-micellar electrokinetic chromatography (FASI-MEKC) method for the determination of 14 benzophenones (BPs) in a food simulant used in migration studies of food packaging materials was developed, allowing almost baseline separation in less than 21 min. The use of a 10 mM sodium dodecyl sulfate (SDS) solution as sample matrix was mandatory to achieve FASI enhancement of the analyzed BPs. A 21- to 784-fold sensitivity enhancement was achieved with FASI-MEKC, obtaining limits of detection down to 5.168.4 µg/L, with acceptable run-to-run precisions (RSD values lower than 22.3%) and accuracy (relative errors lower than 21.0%). Method performance was evaluated by quantifying BPs in the food simulant spiked at 500 µg/L (bellow the established specific migration limit for BP (600 µg/L) by EU legislation). For a 95% confidence level, no statistical differences were observed between found and spiked concentrations (probability at the confidence level, p value, of 0.55), showing that the proposed FASI-MEKC method is suitable for the analysis of BPs in food packaging migration studies at the levels established by EU legislation

FIA-ESI-MS Fingerprinting method with chemometrics for the characterization of adulterated coffee samples

Food products are very complex matrices, which makes the quality of these products an issue of great interest in our society. Considering the complexity of the food chain, the adulteration of food is increasing, causing food fraud cases. In this field, drinks are food products that can be very easily adulterated. This work will focus on the thematic of fraud detection in coffee, one of the most popular beverages in the world. Coffee contains an elevated number of bioactive substances (phenolic acids, polyphenols and alkaloids; being especially abundant ellagic, caffeic and chlorogenic acids) that give place to its important antioxidant activity, known for its beneficial health effects. The aim of this work was to develop an efficient non-targeted FIA-ESI-MS fingerprinting method in combination with chemometrics to achieve the characterization, classification, and authentication of coffee samples, together with possible adulterants (barley, chicory and flours) using partial least squares regression-discriminant analysis (PLS-DA) chemometric method. Besides, Arabica and Robusta coffee samples were adulterated with barley, chicory and flour and the obtained FIA-ESI-MS data subjected to partial least squares (PLS) regression. Results demonstrated the feasibility of the proposed methodology to assess coffee authenticity and to quantify adulteration levels (down to 15%), showing good calibration and prediction errors