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1、質(zhì)譜原理 有機波譜分析 Organic Spectroscopic Analysis Principles of Mass Spectrometry Introduction to Mass Spectrometry（MS,質(zhì)譜）進樣系統(tǒng) 離子源 質(zhì)量分析器 檢測器 Sample Inlet Ion Source Mass Analyzer Detector 記錄儀 Recorder ionizes sample molecules;separates them according to their mass(m)-to-charge(z)ratios(m/z);records a mass

2、spectrum.How does a mass spectrometer work?1.The sample has to be introduced into the ionisation source of the instrument.Once inside the ionisation source,the sample molecules are ionised.2.These ions are extracted into the analyser region of the mass spectrometer where they are separated according

3、 to their mass(m)-to-charge(z)ratios(m/z).3.The separated ions are detected and this signal sent to a data system where the m/z ratios are stored together with their relative abundance for presentation in the format of a m/z spectrum.How does a mass spectrometer work？M e M+Ionization Energy Mass Spe

4、ctrum 質(zhì)譜圖 RI RIrelative intensityrelative intensity（相對強度，%）The RI of the base peak The RI of the base peak（基峰）is 100%.is 100%.其它峰強均用其峰面積相當(dāng)于基峰強度的百分數(shù)表示 Most intense peaks will arise from stable ions and from cleavages that occur most readily 8 2.Ion source(離子源離子源)Electron Impact（EI，電子轟擊離子源），電子轟擊離子源）Ch

5、emical Ionization（CI,化學(xué)電離源）化學(xué)電離源）Field Desorption(FD，場解吸，場解吸)Fast Atom Bombardment(FAB，快原子轟擊，快原子轟擊)Electrospray Ionization(ESI，電噴霧電離，電噴霧電離)Laser Desorption(LD，激光解吸，激光解吸)Matrix Assisted Laser Desorption/Ionization(MALDI，基質(zhì)輔助，基質(zhì)輔助激光解吸電離激光解吸電離)Electron Impact(EI)Very energetic Ions are produced Fragmen

6、tation M.+is often weak or absent (e.g.ROH often loose H2O)Intensity of M.+depends on stability of the Ion:Most Stable Aromatic Conjugated Alkene Cyclic compound Sulfide Short Linear Alkane Mercaptan Least Stable M.+is often absent in:Ketone Amine Ester Ether Acid Amide Aldehyde Alcohols,Nitriles,Ni

7、trates,Nitro M+e(70eV)M+e(70eV)-M M+.+.+2e+2e Ion Source Electron Impact Ionization Source（電子轟擊電離源）Ion Source Electron Impact(EI)Ion Source Chemical Ionization(CI)In CI,ion molecule reactions occur between ionized reagent gas molecules G and volatile analyte neutral molecules(M)to produce analyte io

8、ns.Pseudo-molecular ion MH+(positive ion mode)or M-H-(negative ion mode)are often observed.Unlike molecular ions obtained in EI method,MH+and M-H-detection occurs in high yield and less fragment ions are observed.Positive ion mode:GH+M-MH+G Negative ion mode:G-H-+M-M-H-+G The main reagent gases used

9、 in CI are:Ammonia,Methane,and Isobutane.Choice of reagent gas affect the extend of fragmentation of the quasi-molecular ion.Ion Source Ion Source Proton transfer is one of the simple processes observed in positive CI:RH+M-MH+R One of the decisive parameter in this reaction is the proton affinity.For the reaction to occur,the proton affinity of the molecule M must be higher that the one of the gas molecule.The main reagent gases used in CI are:Ammonia,Methane,and Isobutane.Choice of reagent gas affect the extend of fragmentation of the quasi-molecular ion.Chemical Ionization(CI)Ion Source