Exploring selected modern Mass Spectrometry techniques in applied sciences

Mass Spectrometry (MS) is a powerful analytical technique that has revolutionized our ability to analyze complex mixtures and has diverse applications in various scientific disciplines. It is widely used in chemistry and biology to determine the molecular composition, structure, and quantification of samples. In this dissertation, we aimed to explore novel applications of mass spectrometry techniques, including electrospray ionization (ESI) and tandem mass spectrometry (MS/MS), as well as mass spectrometry imaging (MSI) techniques such as matrix-assisted laser desorption/ionization (MALDI) and desorption electrospray ionization (DESI). The objective was to strengthen our knowledge and skills in various MS methodologies and gain practical experience in using these techniques, for developing methods to chemically profile, separate, detect, map, and quantify a wide range of targeted and untargeted analytes from complex matrices.

Given the versatility of MS-based techniques, we focused on specific applications within this field. First and foremost, forensic and pharmaceutical cannabis-related applications require accurate and sensitive analytical methods. Hence, we developed and validated a DESI-MS method for detecting cannabinoids in cannabis-infused chocolate, utilizing TLC-DESI-MS and QuEChERS extraction for THC quantification.

Additionally, we investigated metabolic differences associated with soybean alleles (QTLs E and M) conferring resistance to leaf-chewing insects. Non-targeted mass spectrometry reveals distinct metabolite sets influenced by the QTLs, highlighting daidzein as a significant marker. This suggests a novel mechanism impeding the insects' ability to evolve tolerance.

Moreover, we explored the sublimation technique for the application of a matrix coating in MALDI-MSI. Specifically, we investigated the optimal conditions for the sublimation of the 5-chloro-2-mercaptobenzothiazole (CMBT) matrix on mouse kidney samples. We successfully obtained high-quality MALDI-MSI images of phospholipids (PC, PG) and phosphatidylinositol (PI) in mouse kidney sections, providing valuable spatially resolved information.

Lastly, we discussed the importance of phosphatidylinositols (PI) and phosphoinositides and their involvement in various diseases, emphasizing the need to optimize the MALDI-matrix type and thickness for enhanced sensitivity in detecting these molecules. The label-free data obtained through this optimized approach holds the potential for investigating the relative m/z factors associated with PI-related pathogenesis.

Overall, this dissertation demonstrated the versatility and potential of mass spectrometry techniques. The findings lay the groundwork for future research in the field of MS analysis, particularly in the detection, quantification, and understanding of phosphatidylinositols and phosphoinositides in biological systems and disease pathologies.