High-throughput screening of solid-phase extraction materials using mass spectrometry

Sammanfattning: In biomarker analysis, sample preparation plays a crucial step in order to extract, isolate and concentrate the analytes of interest. Among the various sample preparation techniques, solid phase extraction (SPE) is one of the most common and popular, due to the high enrichment factor, good recovery, low consumption of organic solvents and the possibility to automate (off- or on-line) the whole process. Over the years, a wide variety of sorbents and affinity phases have been developed and used in SPE. Optimization of a SPE sample preparation step is essential for high sensitivity detection, as well as analysis robustness and reproducibility. However, the process of optimizing the SPE sample preparation in the present commercially available formats can be quite time consuming and expensive, due to the large amounts of SPE phase required and limited options for use of different materials in commercially available configurations. In Paper I, we have applied our micro fabricated SPE sample preparation platform, the Integrated Selective Enrichment Target, (ISET) that interfaces directly with MALDI mass spectrometry for a rapid and parallel investigation of the SPE process using minute amounts of sample. In Paper II, we utilized the 384-well filter plate format for an automated, high-throughput SPE screening method. Compared with the ISET, the 384-well filter plate format provides advantages such as increased bed volume, and thus a larger binding capacity (needed to enable use of low-affinity materials), and can be used with analysis techniques other than matrix-assisted laser desorption/ionization (MALDI), for example, liquid chromatography–electrospray ionization mass spectrometry (LC ESI-MS). However, the developed high-throughput SPE MS optimization platforms generate huge datasets. To handle these huge datasets, MALDIViz, a comprehensive informatics tool for MALDI HTS data that facilitate visualization, statistical analysis, and high quality image and data export was developed in Paper III. In addition to the miniaturized platforms, a conventional cartridge based investigation of custom made SPE materials was undertaken for, SPE ofphosphatidylethanol (PEth), a phospholipid biomarker for alcohol consumption (Paper IV). In Paper V, a newly prepared molecularly imprinted polymer in the form of microgel (MIP MG) stabilized Pickering emulsions (PEs) was investigated for the ability to catalyse the formation of disulphide bonds in peptides at an Oil/Water interface.