Development of Substrate-based Ambient Ionization Techniques for Direct Sampling by Mass Spectrometry

Download or read book Development of Substrate-based Ambient Ionization Techniques for Direct Sampling by Mass Spectrometry written by Sierra Jackson and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mass spectrometry (MS) has evolved into one of the most important methods for the characterization and detection of biological and chemical molecules. The development of soft ionization methods such as electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI) have made these applications possible. However, the requirement for extensive sample preparation has limited analyses that require complex sampling. These limitations in the analysis process have led to the expansion of ambient ionization mass spectrometry. This dissertation describes the development and optimization of novel ambient ionization methods that rely on porous/cellulose-based substrates such as thread and paper. Chapter 2 depicts a thread spray ionization method with forensic serology applications. Thread spray ionization enables direct analysis of trace levels of blood on textiles without extensive sample preparation reducing backlog seen in many criminal laboratories. This dissertation describes the successful implementation of thread spray as a rapid presumptive method of blood-stained textiles through the identification of heme in whole blood. Thread spray ionization is also a suitable confirmatory method through the direct differentiation of human, canine, and horse blood by determining the species’ specific phospholipid lipid profiles. Chapter 3 outlines thread spray ionization as a rapid in situ method for detection of agrochemicals in complex matrices such as surface water and foodstuff. Determination of pesticide residues in a wide variety of matrices is an ongoing challenge due to small quantities of analytes and substantial amounts of interfering substances that can be coextracted with the analytes. In this chapter, we detail the use of a nano-thread spray mass spectrometry approach that utilizes a nano spray like emitter, as opposed to the traditional thread spray ionization apparatus, to enhance on-thread separation of agrochemicals and environmental matrices. This analysis was used for the detection of glyphosate (GLYP) and its metabolite, aminomethylphosphonic acid (AMPA), in surface water. Nano thread spray ionization was then used for the detection of the pesticides diphenylamine (DPA) and thiabendazole on the surface and cores of post-harvest dipped fruits. Chapter 4 describes the development and optimization of a 3-dimensional (3D) wax-printed microfluidic paper-based analytical device, μPAD, for multiplexed disease detection. The 3D wax-printed μPAD is designed for on-line sample splitting, reagent storage, and MS analysis via stacking different layers of two-dimensional (2D) wax-printed paper substrates together. Assembled devices’ transport efficiency were evaluated using Bovine Serum Albumin (BSA-FITC), where μPADs efficiently transported BSA-FITC through devices. We believe the proof-of-concept 3D wax-printed μPAD described in this chapter will be capable of direct multiplex analysis for paper-based immunoassay in resource-limited settings.