Application of matrix compatible solid phase microextraction (SPME) coatings for the analysis in complex food matrices
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In recent years, studies regarding food analysis have increased due to the globalization of food trade as well as concerns about the safety and traceability of food commodities. In this regard, the field of food analysis has seen a substantial increase in the development of analytical methods used to determine the quality and safety of foodstuffs. The most critical step, regarding food analysis, is the sample preparation step, which is considered the most time-consuming step within the complete analysis and one of the most difficult to automate. Solid phase microextraction (SPME) is a well-known sample preparation technique that can be easily automated to overcome the tedious and time-consuming sampling-sample preparation step in the field of food analysis. In SPME, one of the most crucial steps in the SPME protocol is the correct choice of a SPME coating for a given application, as its principle of extraction is based on the degree of distribution between the analytes and the sample matrix. Despite its great potential, the applications of SPME in the analysis of complex matrices, such as food, has been on hiatus due to the lack of suitable SPME coatings that possess compatibility with complex matrices while maintaining sufficient sensitivity for the required applications. Latterly, efforts have been made to the development of coatings that can overcome the issues related to the fouling phenomena, a process that is induced by the matrix components, and that reduces the lifespan of the coatings and affects the extracting selectivity of the analytes directly. One of the recent steps in the development of "matrix compatible coatings" uses one of the most compatible material, the polymer polydimethylsiloxane (PDMS), that used as a coating can present limited extraction efficiency towards less hydrophobic analytes. As an extra layer in the already combined coating that exhibits best extraction efficiency towards contaminants, the polydimethylsiloxane/divinylbenzene (PDMS/DVB) coating, to avoid the attachment of matrix components onto the coating surface, that is a limiting issue for the uses of this solid coating. Therefore, the present thesis established the application and evaluation of a fully automated solid phase microextraction protocol with a complex food matrix using a PDMS/DVB overcoated PDMS fiber. Furthermore, the evaluation of a new automated station was investigated using already established methodologies for complex matrices to enhance the extraction process and guarantee the fiber lifespan. Subsequently, the optimization of the cleaning process was established, defining the optimal parameters for the automated cleaning protocol and then tested to prove the advantages of this new automated method in the maintenance of the lifespan of this matrix compatible coatings for more than 100 extractions. The process was followed by the development of a DI-SPME methodology for the identification and quantitation of contaminants in this fatty matrix using the already establish automated cleaning protocol. Satisfactory figures of merit were obtained from the matrix selected with limits of quantitation for all compounds at ranging between 0.03 and 0.1 µg/g. Additionally, in the final chapter, the applicability of a new gas generating vial with a new solid support is presented as an alternative and more relatable source for a standard gas vial system in high-throughput SPME analysis; the new vial can stand over 300 extractions consecutively with less than 5% of depletion over time/use.
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Paola Ortiz (2020). Application of matrix compatible solid phase microextraction (SPME) coatings for the analysis in complex food matrices. UWSpace. http://hdl.handle.net/10012/15413