Avances en cromatografía de gases para el análisis de microcontaminantes orgánicos persitentes en mezclas complejas

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Químicas, Departamento de Química Analítica, leída el 05-11-2019La cromatografía de gases (GC) es una técnica analítica ampliamente aceptada para la resolución de mezclas de relativa complejidad en la que la identificación se basa en la comparación de los tiempos de retención de los analitos con los de patrones adecuados analizados en las mismas condiciones. Sin embargo, cuando la complejidad de las mezclas estudiadas aumenta, la posibilidad de coelución de los analitos de interés con otros componentes de la mezcla o de la matriz presentes en el extracto también aumenta. Es en estos casos cuando es necesario recurrir a un mecanismo diferente de separación, que pueda dar lugar a una mejor resolución de los compuestos de interés de otros presentes en el extracto a analizar, o incorporar un criterio adicional de separación o identificación que permita evitar ambigüedades en la determinación de los componentes del extracto. Las técnicas multidimensionales resultantes de esta última aproximación permiten una determinación más fidedigna de los analitos al basar su identificación en al menos dos criterios independientes. En el caso de la GC, la multidimensionalidad puede venir dada por su acoplamiento con una segunda técnica de separación cromatográfica o con una técnica de espectrometría de masas (MS) que aporte información estructural referente al analito que eluye de la columna cromatográfica a un tiempo determinado...Gas chromatography (GC) is a widely accepted analytical technique for unravelling the composition of complex mixtures. In GC, the analyte identification relies on the mutual agreement of the retention times of the target analyte and that of a suitable standard analysed under the same experimental conditions. However, as the complexity of the studied mixture increases, the possibility of coelution of the target analytes with other compounds or matrix component present in the extract increases. Under these circumstances, the use of a different separation mechanism, which can result in an improved resolution of the test analytes from other compounds present in the extract, or the adoption of an additional separation or identification criterion, becomes mandatory. The multidimensional techniques resulting from the later approach should allow an unambiguous analyte determination based on at least two independent identification criteria. In the case of GC, that second identification criterion (i.e., multidimensionality) can derive from the hyphenation of GC with a second chromatographic separation technique or with a mass spectrometry-based (MS) technique which provides structural information...Depto. de Química AnalíticaFac. de Ciencias QuímicasTRUEunpu

Non-target screening of halogenated microcontaminants in tuna samples by GCxGC-ToF MS

Trabajo presentado a la XV Reunión Científica de la Sociedad Española de Cromatografía y Técnicas Afines (SECyTA) celebrada en Castellón de la Plana del 28 al 30 de octubre de 2015Comprehensive gas chromatography coupled to a time-of-flight mass spectrometer analyzer (GC×GC−TOF MS) is recognized as a powerful separation technique that, when combined with an appropriate (generic) sample preparation technique, can provide information simultaneously for targeted and non-targeted compounds [1]. In this type of study, the feasibility of the technique to generate structured chromatograms is an additional feature that contributes to the identification of analytes and families of analytes for which standards are not available and so to the (virtual) identification of known-unknown and unknown compounds when only mass spectral information is available. However, when analyzing complex extracts, the manual inspection of all compounds detected, even for a particular region of the contour plot, can be a tedious and laborious work. For these types of samples, when the interest focus on a particular category of compounds, the use of classification tools can effectively contribute to further reduce the initial data set through its automatic filtering on the base of, for example, specific structural characteristics. In this work, classifications and scripts (mass spectral filtering) software was employed to process data generated using GC×GC−ToF MS for bluefin tuna muscles subjected to a rather generic sample preparation procedure, i.e. Soxhlet extraction and acidic fat removal [1]. The script function was based on that reported on [2] and described to recognize a generic halogenated isotope cluster pattern. Therefore, in practice, it allowed the automatic and simultaneous filtering and visualization on the contour plot of the detected chlorinated, brominated, or mixed Cl-Br compounds in the investigated samples. Once optimized, the proposed scripting and classification tool allowed the successful classification of 96% of the halogenated compounds present in a standard mixture containing 114 compounds, including PCBs, organochlorinated pesticides, PBDEs, MeO-PBDES, PBBs, and other naturally occurring organobrominated compounds. When applied to the analysis of a real tune extract, it resulted in a significant reduction of the time required for data treatment by identifying as organohalogenated among only some 4-5% of the ca. 10000-5000 initially detected peaks. Manual inspection of this sub-data set revealed an average identification accuracy of ca. 75%. Up to know, 249 chlorinated-, brominated- and mixed Cl-Br- compounds belonging to 20 general classes were identified in the 10 Mediterranean bluefin tuna muscles investigated. Identified compounds included targeted and non-targeted legacy, emerging and naturally occurring compounds. [1] M. Pena-Abaurrea, A. Covaci, L. Ramos, J. Chromatogr. A 1218 (2011) 6995-7002. [2] M. Pena-Abaurrea, K. J. Jobst, R. Ruffolo, L. Shen, R. McCrindle, P. A. Helm, E. J. Reiner. Environ. Sci. Technol. 48 (2014) 9591-9599. Acknowledgements. Authors thank MINECO for funding (CTQ2012-32957).Peer reviewe

The latest trends in the miniaturized treatment of solid samples

Miniaturization is a recognized trend in many analytical application areas, including the analysis of trace organic compounds in food and environmental samples. The many impressive advances achieved in recent decades in the analytical instrumentation used in this study area allowed a progressive reduction in the initial amount of sample used for analytical determinations without affecting the accuracy of the final result. This evidence promoted the development of a plethora of novel, miniaturized, analytical techniques for the treatment of liquid matrices. However, progress in the treatment of (semi-)solid matrices was much more limited, probably due to the greater complexity of the matrices and the persistent lack of appropriate small-scale instrumentation. Despite these shortcomings, research in this field remains active. This review covers recent advances and the latest trends in this research area.Authors thank MINECO (CTQ2012-32957), the Community of Madrid (S2013/ABI-3028, AVANSECAL-CM) and the European founding from FEDER program, for financial support.Peer Reviewe

Evaluation of the selectivity of ionic liquid-based gas chromatographic columns

Author thanks MICINN, Comunidad of Madrid and European funding from FSE and FEDER for projects AGL2016-80475-R and S2018/BAA-4393 (AVANSECAL-II-CM

Statistical comparison of the retention mechanism of polychlorinated biphenyls in different gas stationary phases

Author thanks MICINN, Comunidad of Madrid and European funding from FSE and FEDER for projects AGL2016-80475-R and S2018/BAA-4393 (AVANSECAL-II-CM