Chemistry Proposal Defense Seminar – Elvin Cabrera
About the event
Title: Tailored Non-Linear Signal Modulation to Increase Confidence in Multiplexed IMS Measurements
Abstract: Frequency modulated ion mobility spectrometry (IMS) experiments have allowed efficient interfacing with ion trap mass spectrometers despite the duty cycle mismatches. Furthermore, concomitant benefits such as improved signal to noise ratios, throughput, and drastically reduced experimental times are also realized. Despite successful applications of these methods, a degree of ambiguity exists upon interpreting the time-domain signal generated by FT-IMS experiments. Generally, ion gates are modulated according to a predefined range of frequencies (e.g., 5-8005 Hz) in a semi-continuous manner and only requiring the start and end of the ion mobility and mass spectrometry experiments to align. Due to the comparatively slow scan rates of ion traps, this allows multiple frequencies to be generated between two consecutive mass scans. This therefore creates uncertainty when attempting to assign a single frequency value to a particular data point within the generated time-domain signal, and by extension, determination of an ion’s mobility. Addressing these shortcomings, our work aims eliminate the ambiguities within frequency assignment by implementing synchronized sweeps where gates are frequency modulated in a stepwise manner. This approach allows for complete confidence that each point within the time-domain signal reflects ion current that is resonant with the corresponding frequency. We also aim to further improve the efficiency of FT-IMS experiments by shifting from the traditional approach of linear frequency modulation towards non-linear frequency modulation for targeted and untargeted analysis in order to reduce the amount of oversampling and uninformative signal. To this end, we aim to implement these techniques in order to effectively capture the temporal dynamics of transient molecular species created late in the lifetimes of f-element plasmas.