Sample preparation is an essential component of analytical methods in chemistry. It is not only necessary but also presents an opportunity to increase the effectiveness of the method significantly. There are various commercially available technologies for sample preparation, including numerous variations of LLE, SPE, and SPME. However, these technologies all present significant deficiencies, including the inability to extract directly from complex samples such as whole milk. Instrumental analysis has been improved greatly in the last two decades but still is not applicable to complex samples without sample preparation.
This work presents the theory of FPSE, including the synthesis of sol-gel sorbents, coating of FPSE cellulose substrates and the mechanism of retention. Original research data presented herein introduce a comprehensive view on possible applications of FPSE in forensic chemistry and otherwise. Five distinct FPSE-based methods were rigorously developed for analysis of targeted pollutant residues. These methods were validated and compare to leading methods published in peer-reviewed literature quite favorably. Four of the methods were coupled to HPLC-UV and designed for trace or ultra-trace analysis of PAHs, BTEX, substituted phenols and nitroaromatic explosives, respectively. An additional FPSE-based method was developed and validated for direct analysis of BPA and five estrogenic EDCs in commercially purchased whole milk. This latter was coupled to both HPLC-UV and HPLC(QQQ)-MS/MS.
The applicability of FPSE(PTHF) media was also tested for screening of aqueous samples and subsequent storage of analytes on the sorbent. My study included simultaneous extraction of a mixture of eight forensically significant compounds with various physicochemical properties and effective storage of each compound in frozen and ambient conditions for 32 weeks. These findings suggest that the storage ability of FPSE media can be extended as long as necessary, which is very significant in forensic laboratories where evidence often needs to be stored in a costly manner that may not be as effective in maintaining the chemical composition of the sample.
| Identifer | oai:union.ndltd.org:fiu.edu/oai:digitalcommons.fiu.edu:etd-4618 |
| Date | 26 October 2017 |
| Creators | Mesa, Rodolfo |
| Publisher | FIU Digital Commons |
| Source Sets | Florida International University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | FIU Electronic Theses and Dissertations |
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