Innovative mass spectrometry-based analytical strategies in proteomics

This PhD thesis was divided in four main sections. In particular, the first section is composed by fourth chapters showing the main components of a mass spectrometer such as sources, analyzers and detectors followed by a brief introduction of mass spectrometry-based proteomics. In the second chapter, the proteomics analysis of platelet-derived microparticles under different agonist stimulations has been described. In the third chapter, the PTMs analysis of platelet-derived microparticles has been presented. In particular, phosphorylation and glycosylation have been intensely studied. In the fourth chapter, different sample treatment methods for the simultaneous quantification of caseins and ovalbumin in red wine have been investigated. This thesis has presented an overview of mass spectrometry-based analytical strategies in proteomics and has shown that mass spectrometry has become essential in the protein analysis in both biological and food samples

Optimization of a rapid QuEChERS sample treatment method for HILIC-MS2 analysis of paralytic shellfish poisoning (PSP) toxins in mussels

A rapid and simple QuEChERS sample treatment was proposed for the development of a selective hydrophilic interaction liquid chromatography-ESI-MS2-based method for the determination of saxitoxins (STXs) in mussel samples. Among different sorbents, ABS Elut-NEXUS phase, composed of polystyrene cross-linked with 50 % divinyl benzene and poly(methyl methacrylate), provided the best results. The effects of experimental parameters, including sorbent amount, vortexing time and centrifugation time were investigated and optimized by experimental design. In particular, regression models and desirability functions were applied to find the experimental conditions providing the highest global extraction response. The method was validated under the optimized conditions; detection and quantification limits in the 3-159 μg/kg and 7-436 μg/kg ranges respectively were obtained, except for C2 for which highest values were calculated due to its low ESI ionization efficiency. Finally, the analysis of twenty-eight mussel samples permitted to detect and quantify some of the investigated STXs, proving the applicability of the devised method

Introduzione all'analisi dei dati statistici. Ediz. ampliata

Questo testo illustra gli argomenti classici della statistica descrittiva riferita a uno e due fenomeni: la rilevazione dei dati e la loro presentazione in forma tabellare o grafica, le medie, le misure della variabiità, gli indici della forma di distribuzione, le relazioni tra due variabili sia in termini di correlazione, sia con riferimento alla retta di regressione

Rapid desorption electrospray ionization-high resolution mass spectrometry method for the analysis of melamine migration from melamine tableware

Migration of melamine into foods from melamine tableware has been object of recent Rapid Alert System for Food and Feed (RASFF) notifications. In this context, a rapid and sensitive desorption electrospray ionization-high resolution mass spectrometry (DESI-HRMS) method was developed and validated for the determination of melamine migration from plastic materials. The migration test was performed using acetic acid 3% (w/v) as food simulant. Evaluation of DESI parameters in terms of choice of support, motion profile, geometrical configuration and operating conditions coupled to the use of an orbitrap mass analyzer allowed to achieve significant improvements in terms of selectivity and accuracy obtaining detection and quantitation limits at low microgram per kilogram level. A LC–ESI-MS method was also developed for confirmatory purposes. Both methods were applied to 44 melamine tableware samples available on Italian market in order to assess their compliance with the law. Different concentration levels ranging from 0.0077370.0006 to 3.070.1 mg/kg were found after the third exposure to the simulant in new and used tableware with two samples out of 44 being characterized by a melamine release higher than the legal limit, i.e. 2.5 mg/kg. A two tailed t-test allowed to assess the good agreement between the quantitative results obtained applying the DESI-MS method with those provided by LC–ESI-MS, thus proving reliability of DESIHRMS as rapid technique for the study of melamine release from plastic materials

An innovative method based on quick, easy, cheap, effective, rugged, and safe extraction coupled to desorption electrospray ionization-high resolution mass spectrometry for screening the presence of paralytic shellfish toxins in clams

The capabilities of desorption electrospray ionization-high resolution mass spectrometry (DESI-HRMS) were tested for screening the presence of some paralytic shellfish toxins in clams. A quick, easy, cheap, effective, rugged, and safe (QuEChERS) approach is proposed for sample clean-up.QuEChERS extraction was optimized by using a full factorial design followed by the multicriteria method of the desirability functions. Quantitation limits in the microgram pe rkilogram range proved reliability of the method for the detection of the investigated toxins in accordance to the rules laid down by European legislation. The optimized QuEChERS-DESI-HRMS based-method allowed for a rapid reliable screening of the in- vestigated compounds at levels of interest, thus being useful for high-throughput analyse

EEG spectral coherence analysis in nocturnal epilepsy

Objective: Electro-encephalographic (EEG) is widely employed in the study of sleep disorders. The present work exploits the identification of cyclic alternating patterns (CAP), a periodic ubiquitous phenomenon nested in the sleep stages, to analyze the EEG spectral coherence in subjects affected by nocturnal frontal lobe epilepsy (NFLE) with respect to controls. Methods: For each EEG recording we extracted several CAP A1 subtype 4 seconds timeseries. We analyze the coherence between each pair of electrodes for each individual to obtain its distribution for each frequency range of interest to investigate differences between cases and controls. In addition, the imaginary and real parts of the spectral coherence were calculated and plotted to assess their likelihood of segregation into different classes and anatomical regions. Results: The results of this study suggest a relevant frontal-temporal neural circuitry difference between individuals affected by epilepsy and controls. Conclusion: This supports the observation that, though highly variable, a broad range of executive, cognitive and attentional deficit observed in subjects affected by NFLE might depend on frontal-temporal altered networking. Significance: The investigation of EEG activity in the domain of the complex sleep architecture represents a challenging topic in neurophysiology and needs new methods to explore the manifold aspects of sleep. This work aims to provide a simple method to distinguish NFLE from healthy subjects from a functional connectivity point of view and to explore the possibility of using a smaller EEG channel set to support diagnosis