气溶胶单粒子的检测效率与基质辅助激光解吸电离研究

利用基质辅助激光解吸电离(MALDI)技术,在自行研制的气溶胶飞行时间质谱仪(ATOFMS)上实时探测单个生物气溶胶粒子的粒径和化学成分。采用双束激光空气动力学方法进行气溶胶粒子粒径的测量,并用266 nm的Nd∶YAG激光器对粒子进行激光解吸电离。以2,5-二羟基苯甲酸(DHB)和芥子酸为基质,对多肽生物样品进行了实验研究。质谱峰中质子化的分析物阳离子是在气相时,和基质通过质子转移反应形成的;而分析物碱金属加和物阳离子是在气相离子分子反应中,通过气相阳离子转移反应形成的。气溶胶粒子的检测效率为0.01%左右,命中率为10%左右。实验结果表明,该仪器可以满足大气中气溶胶单粒子的实时在线检测。

Investigation of Individual Aerosol Particles Detection Efficiency and Matrix Assisted Laser Desorption/Ionization

The size and the chemical composition of an individual bioaerosol particle were detected in real-time by matrix-assisted laser desorption/ionization (MALDI) on the home-built aerosol time-of-flight mass spectrometer (ATOFMS). The size of the aerosol particles was measured using two laser beams aerodynamic method, and the MALDI mass spectra were obtained using 266 nm pulsed Nd:YAG laser. Experiments were performed using polypeptide as analyte and 2,5-dihydroxybenzoic acid (DHB) and sinapic acid as matrices. The protonated analyte ion was generated by gas-phase proton transfer with matrix, while the adducts ion of analyte was generated by gas-phase cation transfer reaction with alkali metals ion. Detection efficiencies of aerosol particles were measured to be ～0.01%, and the hit rates were measured to be ～10%, showing that the ATOFMS is eligible for the real-time detection of aerosol particles in atmosphere.