质谱Mass spectrometry

质谱仪由进样系统、离子源、质量分析器、检测器和数据系统组成，在高真空下工作。离子源：电子轰击（EI，硬电离，碎片丰富）、化学电离（CI）、电喷雾（ESI）、基质辅助激光解吸（MALDI）、大气压化学电离（APCI）等。质量分析器：磁扇形、四极杆、离子阱、飞行时间（TOF）、轨道阱和傅里叶变换离子回旋共振（FT-ICR）。高分辨质谱（分辨率 > 10⁴）可测定精确质量（误差 < 5 ppm），区分 CO（27.9949）、N₂（28.0061）和 C₂H₄（28.0313）。串联质谱（MS/MS）使选定离子碎裂，获得结构信息。

A mass spectrometer has an inlet, ion source, mass analyser, detector and data system and runs under high vacuum. Ion sources include electron ionisation (EI, hard, with many fragments), chemical ionisation (CI), electrospray (ESI), matrix-assisted laser desorption (MALDI) and atmospheric-pressure chemical ionisation (APCI). Analysers include magnetic sectors, quadrupoles, ion traps, time-of-flight (TOF), Orbitraps and Fourier-transform ion cyclotron resonance (FT-ICR). High-resolution MS (resolution above 10⁴) measures exact masses to within 5 ppm, distinguishing CO (27.9949), N₂ (28.0061) and C₂H₄ (28.0313). Tandem MS (MS/MS) fragments selected ions for structural information.

1897 年汤姆孙测定电子的荷质比，1912 年用抛物线质谱仪发现氖的两种同位素 ²⁰Ne 和 ²²Ne。1919 年阿斯顿制成质谱仪，发现了 212 种天然同位素，获 1922 年诺贝尔化学奖。二战期间质谱用于铀同位素分离。1980 年代芬恩发明电喷雾电离、田中耕一发明软激光解吸电离，使蛋白质等生物大分子的质谱分析成为可能，二人获 2002 年诺贝尔化学奖。

Thomson measured the electron's charge-to-mass ratio in 1897 and in 1912 used his parabola spectrograph to find two isotopes of neon, ²⁰Ne and ²²Ne. Aston built his mass spectrograph in 1919, identified 212 natural isotopes and received the 1922 Nobel Prize in Chemistry. Mass spectrometry separated uranium isotopes during the Second World War. In the 1980s Fenn invented electrospray ionisation and Koichi Tanaka soft laser desorption, making MS of proteins and other biomacromolecules possible; they shared the 2002 Nobel Prize in Chemistry.

质谱用于有机化合物分子量和结构鉴定、蛋白质组学（肽段测序和翻译后修饰）、代谢组学、药物代谢动力学、新生儿遗传代谢病筛查、兴奋剂与毒品检测、环境痕量污染物分析、同位素地质测年和示踪、同位素比值质谱用于食品产地溯源，以及航天器上的行星大气分析。

MS determines molecular weights and structures of organic compounds and is used in proteomics (peptide sequencing and post-translational modifications), metabolomics, pharmacokinetics, newborn screening for inherited metabolic disorders, doping and drug testing, trace environmental analysis, isotopic dating and tracing, isotope-ratio MS for tracing the origin of foods, and analysis of planetary atmospheres by spacecraft.