Study Of Mass Spectrometry Ionization Method And Spectroscopic Data Manipulation

Mass Spectrometry(MS)is a kind of analytical method that isolates and detects ions by their mass-to-charge ratios(m/z).MS has been widely used in analytical fields of food,drugs,explosives,biological samples and so on for its advantageous features such as high sensitivity,high specificity,high efficiency and capability of simultaneous detection of multiple components.The development of ionization method and efficient utilization of MS data have played very important roles in the fast development of MS technology.Ion sources with higher sensitivity and better anti-interference ability are under discovering,and more MS data processing techniques are still in demand.Herein we developed a new ion source and a new spectrometric data processing strategy with simplicity and effectivity.In our first work,we developed a new ion source termed Paper Cone-Desorption Electrospray Ionization(PC-DESI)basing on Nano-Electrospray Ionization(Nano-ESI)and Desorption Electrospray Ionization(DESI).An open paper cone is wrapped around a Nano-ESI source to act as a desorption substrate.Charged solvent droplet is generated in the Nano-ESI source and desorbs sample on the substrate.Then sample ions are transferred through the paper cone to enter the mass spectrometry.Compared to conventional DESI,PC-DESI has 3 main advantages:1.Higher sensitivity and signal intensity.The Nano-ESI source,axis of paper cone and MS inlet are collinear,thus samples are ionized and transferred directly.The paper cone provides more chances for solvent droplets to desorb sample and preserves ions in a restricted area.These factors ensure a higher sample ionization and transfer efficiency.2.The improvement of desorption efficiency decreases ions from the solvent,resulting in much cleaner mass spectra.3.The involvement of Nano-ESI not only cuts down the solvent requirement,but also simplifies the equipment installation by discarding the nebulizing gas.In our second work,we developed a new data processing strategy termed quantitative principal component analysis(qPCA)to automatically resolve complex spectroscopic data of multicomponent system and calculate quantities of each component.In this paper we illustrated the principle and method of qPCA,and further verified it with both model spectra generated by computer and experimental data of Raman spectroscopy(RS),Fourier transformed-infrared spectroscopy(FT-IR),ultraviolet-visible spectroscopy(UV-vis),nuclear magnetic resonance(NMR)and MS.It turns out that qPCA is capable of quantify multi-component systems with high accuracy and it's much superior to manual calculation method and Multivariate Curve Resolution-Alternate Least Square(MCR-ALS).