Construction Of Mass Spectrometry Detection System With Atmospheric And Open Laser Desorption/Ionization Set

Mass spectrometry is a powerful technique for material analysis.It has developed rapidly in recent years and has become an indispensable research tool in many fields such as proteomics and tissue imaging.Surface-assisted laser desorption ionization(SALDI)is a matrix-free laser desorption ionization mass spectrometry method that uses a nanomaterial substrate to absorb laser energy and transfer energy to the analyte while avoiding direct laser damage to the sample and reducing analysis debris.Since SALDI does not use a matrix,organic small molecules are not introduced,eliminating the background signal when detecting low molecular weight samples.Due to the slow light effect,when the group velocity of light is close to the photon forbidden band edge of the substrate,the absorption of light by the substrate and the interaction time of the light and the material can be increased,so as to enhance the effect of desorption ionization of the sample.This article builds a laser desorption ionization mass spectrometry detection system that does not require the use of substrates and can be injected under atmospheric pressure and open atmosphere.The system mainly includes nanosecond laser light path,scanning platform,and atmospheric sample injection.The specific research work is as follows:(1)Using optical parametric oscillators,laser mirrors,polarizers,and convex lenses to form the optical path,a 355 nm wavelength laser is focused on the sample stage as a spot for desorption ionization.Measure and calculate the reflectivity of the mirrors in the optical path at all levels,verifying that the optical path can fully meet the experimental requirements of desorption ionization.Laser control is programmed using LabVIEW and features include on/off,trigger start/stop,Q-Switch settings,and more.(2)Use a sample stage,a Z-axis lift platform,a two-dimensional mobile platform,and an aluminum alloy base to build a scanning platform.Using LabVIEW programming to achieve the control of the scanning platform,the control program has two modes of platform movement and platform scanning,which greatly facilitates the experimental operation and lays the foundation for the subsequent realization of MS scanning imaging.(3)The atmospheric mass spectrometry sample injection method was explored.In this article,SALDI mass spectrometry is performed under atmospheric pressure and the sample analysis is susceptible to various impurity ions in the air.In order to increase mass spectrometer sampling efficiency and signal quality,three different mass spectrometry methods have been tried.The use of an aerodynamically assisted high voltage electric field eventually resulted in good mass spectrometry signals.(4)Explore the impact of different laser power and voltage on mass spectrometry signals.After analysis,it is considered that laser power 35 mW and voltage 2 kV are the best experimental parameters.