Nuevas estrategias analíticas para la determinación de Hidrocarburos Aromáticos Policíclicos e inhibidores selectivos de la Ciclooxigenasa-2 en muestras medioambientales

La presente Tesis Doctoral ha abordado el estudio de dos familias de compuestos: los hidrocarburos aromáticos policíclicos (PAHs) y los anti-inflamatorios no esteroideos que actúan como inhibidores selectivos de la ciclooxigenasa-2, designados como COXIBs. Las técnicas analíticas desarrolladas se basan en una primera etapa de preparación de muestra dirigida a matrices de carácter medioambiental (aguas residuales y lodos, principalmente) y una segunda etapa de determinación mediante técnicas cromatográficas. Para afrontar el estudio de los contaminantes orgánicos (PAHs) en matrices acuosas, se seleccionó la extracción sorptiva con ad/absorbentes poliméricos siendo la cromatografía líquida de ultra eficacia con detección mediante fluorescencia y ultravioleta (UPLC-FD/UV) la técnica de determinación. Para el estudio de los contaminantes emergentes (COXIBs) se han empleado dos técnicas analíticas en función del tipo de matriz a tratar. En el caso de aguas residuales (influente y efluente) se ha aplicado la extracción en fase sólida (SPE) mientras que en el caso de muestras sólidas como son los lodos, la dispersión de matriz en fase sólida (MSPD) ha sido la opción seleccionada. Finalmente, estas técnicas se combinaron con procedimientos de determinación mediante cromatografía líquida seguida de un analizador de masas híbrido de tipo cuadrupolo tiempo de vuelo (QTOF) de última generación

Matrix solid-phase dispersion followed by liquid chromatographytandem mass spectrometry for the determination of selectiveciclooxygenase-2 inhibitors in sewage sludge samples

A straightforward single-step extraction method based on matrix solid-phase dispersion (MSPD), followed by high-performance liquid chromatography with hybrid quadrupole time of flight mass spectrometry (LC–QTOF-MS), was developed and optimized to determine five non-steroidal anti-inflammatory drugs (Valdecoxib, Etoricoxib, Parecoxib, Celecoxib and 2,5-Dimethylcelecoxib) in sewage sludge samples. The influence of different operational parameters on the extraction efficiency a well as in the matrix effects of the produced extracts was evaluated in detail. Under final working conditions, freeze dried samples (0.2 g) were first soaked with 100 μL of aqueous potassium hydroxide solution (60%, w/v), mixed with 1 g of anhydrous sodium sulfate and dispersed with 1 g of Florisil. This blend was transferred to the top of a polypropylene column cartridge containing 3 g of silica. Analytes were recovered using 15 mL of hexane/acetone (1:2, v/v) mixture. The extracts were concentrated by evaporation and reconstituted with 1 mL of methanol/water (1:1, v/v), filtered and injected in the LC system. Quantification limits from 0.005 and 0.05 ng g−1 and absolute recoveries between 86 and 105% were achieved. Results indicated the presence of two of the targeted COXIBs in real samples of sewage sludge, the highest average concentration (22 ng g−1) corresponding to celecoxib. Moreover, the screening capabilities of the LC–QTOF-MS system demonstrated that the developed MSPD extraction procedure might be useful for the selective extraction of some other pharmaceuticals (e.g. amiodarone and their metabolite N-desethylamiodarone, miconazole, clotrimazole and ketoprofen) from sludge samplesThis study has been supported by the Spanish Government and E.U. FEDER funds (project CTQ2015-68660-P) and Xunta de Galicia (GRC2013/020)S

A new strategy for the computer-assisted development of reversed-phase liquid chromatography separation methods of unknown sample mixtures

new strategy for the computer-assisted methods development in the reversed-phase liquid chromatographic separations of unknown sample mixtures has been developed using the latent spectral information in chromatogram raw data files of appropriately designed experiments, rather than resorting to elemental information functions (e.g., the number of peaks in chromatograms or similar criteria). The strategy developed allows unification of the approach for samples of both known and unknown composition and, thus, provide a general strategy for computer-aided tools in the chromatography laboratory. The operation principle of this strategy departs from extracting the spectra of components in the mixture chromatograms by resorting to multivariate curve resolution-alternating least squares (MCR-ALS). This technique allows the estimation of the true spectra for the individual components except when they have identical spectra or are fully overlapped. Thus, a convenient experimental design will try to perform separations of the sample mixture having at least partial resolution of components in some runs. This will allow estimating the spectra of components and, then, assign these components to the peaks in each run chromatogram. In this way, a retention model can be built for each component so computerized optimization process can be developed to provide the chromatographer with the best possible separation programs. Following this approach, strategies for sample mixtures of known and unknown composition are only different in the need of an initial spectrum discovery process for unknown mixtures and therefore a real general approach for the computer-assisted LC methods development is now available for the first timeOpen Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was supported by GAIN (Axencia Galega de Innovación) through the Programa Industrias de Futuro 4.0 and co-financed by the European Regional Development Fund (ERDF) under the Feder Galicia 2014-2020 operational program and the Consellería de Economía, Emprego e Industria within the project “Laboratorio Dixital do Futuro (FutureLab” (IN854A 2019/16)S