Improvements on real-time, gas-phase, analytical chemistry instrumentation

En esta Tesis Doctoral se han desarrollado mejoras en los componentes de un sistema de análisis químico de vapores en tiempo real basado en espectrometría de masas (MS). Este sistema está formado por varias etapas conectadas en serie, de las cuáles dos han sido objeto de estudio: la ionización (SESI) y la separación por movilidad (TMIMS). El objetivo de este trabajo ha sido optimizar tecnologías ya existentes, pero sólo en fase de prototipo. La herramienta de trabajo fundamental ha sido la simulación numérica, que para este trabajo ha tenido que ser formulada y validada. Los resultados mostrados en esta Tesis Doctoral auguran que un sistema SESI-TMIMS-MS puede llegar a ser una interesante herramienta de análisis de vapores de prestaciones equiparables (e incluso superiores) a la técnica dominante en el momento de realizar ese trabajo: GC-MS (cromatografía de gases con espectrometría de masas).Departamento de Ingeniería Energética y FluidomecánicaDoctorado en Ingeniería Industria

A novel valveless pulsatile flow pump for extracorporeal blood circulation

Producción CientíficaExtracorporeal Membrane Oxygenation (ECMO) is a modality of extracorporeal life support which allows temporary support in cases of cardiopulmonary failure and cardiogenic shock. This study presents a valveless pump that works by the Liebau effect as a possible pumping system in ECMO circuits, replacing the current roller and centrifugal pumps. For this purpose, a mock circulatory loop emulating the haemodynamic of the right part of the heart has been constructed. A VV-ECMO circuit with the integrated Liebau pump has been incorporated to analyse its performance. The Liebau pump in the ECMO circuit showed a flow assistance in the range of paediatric ECMO and low blood flow range for adults. In addition, Experimental test conducted demonstrated the advantage of the Liebau pump over currently used pumps as the ability to generate a pulsatile flow, which has many advantages in biomedical applications

Numerical modeling and experimental validation of a universal secondary electrospray ionization source for mass spectrometric gas analysis in real-time

The process by which ambient vapors are ionized upon interaction with electrosprays is not fully understood, compromising its optimization and widespread use. In this work we evaluated the different scales associated with the processes involved in secondary electrospray ionization (SESI), and developed a new numerical method that merges the analytical solution that describes the angle of aperture and the current of an ideal electrospray, with a finite element method that enables the evaluation of complex geometries. The numerical method showed that, despite the low ionization efficiency (i.e. ion concentration/neutral vapor concentration ∼10−4), depletion of neutral vapors plays an important role. We used this method to optimize and design a low flow SESI source, which was coupled with a commercial high resolution/high mass accuracy mass spectrometer. The system was designed to be interfaced with virtually any pre-existing atmospheric pressure ionization mass spectrometer. The experimental validation for the detection of ambient vapors confirmed qualitatively the numerical predictions in terms of ionization efficiency as a function of sample flow rate. As a result of the optimization, this prototype showed a 5-fold sensitivity increase against standard SESI. This novel add-on is meant to upgrade mass spectrometers to analyze trace gases in real time by SESI technique.ISSN:0925-400

An assessment of the suitability of a Liebau pump in biomedical applications

Impedance pumping and asymmetric pumping are the main mechanisms of the Liebau effect, a type of valveless pumping. The primary objective of this study is to enhance the current understanding of the mechanics and functionality of a Liebau pump. To achieve this, a prototype pump is constructed, incorporating several novel features: a pinch frequency control system to optimize pump performance, a planar actuator developed using soft robotic technology, and a compliant chamber designed to mitigate flow fluctuations and prevent reverse flow, a common feature of this pumping method. Experimental tests conducted with this prototype demonstrate that the Liebau pump holds potential as a viable technology for fluid pumping in biomedical applications, especially when pulsatile flow is essential or when hemolysis needs to be minimized.Junta de Castilla y León, proyecto VA182P2

Real-Time High-Resolution Tandem Mass Spectrometry Identifies Furan Derivatives in Exhaled Breath

ISSN:1520-6882ISSN:0003-270

Real-time chemical analysis of e-cigarette aerosols by means of secondary electrospray ionization mass spectrometry

Chemical analysis of aerosols collected from electronic cigarettes (ECs) has shown that these devices produce vapors that contain harmful and potentially harmful compounds. Conventional analytical methods used for the analysis of electronic cigarettes do not reflect the actual composition of the aerosols generated because they usually neglect the changes in the chemical composition that occur during the aerosol generation process and after collection. The aim of this work was to develop and apply a method for the real-time analysis of electronic cigarette aerosols, based on the secondary electrospray ionization technique coupled to high-resolution mass spectrometry, by mimicking the "vaping" process. Electronic cigarette aerosols were successfully analyzed and quantitative differences were found between the liquids and aerosols. Thanks to the high sensitivity shown by this method, more than 250 chemical substances were detected in the aerosols, some of them showing a high correlation with the operating power of the electronic cigarettes. The method also allows proper quantification of several chemical components such as alkaloids and flavor compounds