Colloidal/Solid Phase Extraction (C/S PE) Methods Based on Hydrogel Nanoparticles, Titanium dioxide microparticles and Empore Membranes Applied to Biological and Environmental Matrices

Abstract: The aim of the work described in this thesis was to create and develop novel technologies in order to overcome barriers and hurdles that analytical chemistry faces focusing on sample extraction. In paper I dye containing amine groups (e.g. Acid Black 48, Remazol Brilliant Blue R) were coupled to NIPA/Acrylic acid (AAc) particles by condensation of the amine group and the carboxylic group. The high affinity between dyes and proteins allow for fast kinetics and complete depletion of the supernatant and protection of the captured analyte from enzymatic degradation. The ability of particles to capture and concentrate analytes was tested against a panel of low abundance, labile tumor relevant biomarkers and in serum. Results indicate that the nanoparticles increased the sensitivity limit of mass spectrometry analysis and that the dye based baits have extremely high affinity for the target analytes so that particles capture all the analyte present in solution. Biomarker harvesting nanoparticles may be useful for discovery of novel diagnostic analytes, can increase the sensitivity of detection for analytical methods such as immunoassays and MS, and protect labile biomarkers from degradation during collection, shipment and storage. In paper II and paper III, applications of hydrogel nanoparticles to serum samples from cancer patients are reported. Hydrogel nanoparticles were integrated in a mass spectrometry based workflow for the discovery of candidate biomarkers. Lists of candidate biomarkers were identified that are under verification and validation. In paper IV and V hydrogel nanoparticles functionalized with dyes, were employed to increase the sensitivity of diagnostic test for Lyme disease and to detect human growth hormone (hGH) in urine samples. In paper VI, titanium dioxide (TiO2) microparticles were used to pack fused silica capillary column and used to capture and enrich phosphopeptides in vitreous samples. In paper VII, Empore disk membranes were used to capture organophosphates (OPEs) flame retardant from air samples. Empore disk membranes were used as on- line extraction followed by reverse phase liquid chromatography tandem mass spectrometry (RPLC-MS/MS) analysis. Optimized “geometry” settings were used to strip semi volatile and volatile compounds from C8 membrane. This novel design allowed for a better analyte focusing in the HPLC column, reduced the volume of the organic solvent employed for the extraction and the analysis time, and eliminated sample contamination, and loss of analyte.