Interpretation of mass spectra of organic compounds pdf

Positive and negative ion LDI mass spectra of phenanthridine. Figure 3. Positive and negative ion LDI mass spectra of perinaphthenone. A number of oxygenated PAHs were characterized using 2. Aromatic and Functionalized Aromatic Hydrocarbons. Positive and negative ion spectra for perinaphthenone A large variety of smaller aromatic and functionalized aromatic are displayed in Figure 3. In the positive ion spectrum, the parent compounds may be found in atmospheric particulate matter.

All oxygenated PAHs produced a small 2 lists monocyclic aromatic compounds and derivatives that have parent ion when sampled as pure particles. Aromatic hydrocarbons exhibit observed in the positive ion spectra of oxygenated PAHs are low- mass spectra that are, in general, similar to the PAHs. Large peak intensities common with heterocylic compounds. The base peak in these are observed for low-mass carbon fragment ions, similar to PAHs.

In the Figure 3b. This contrasts previous studies with LAMMA, where positive ion mass spectrum, a fairly large parent ion is observed deprotonation to form the M - H - ion dominates. The only major peaks observed in the spectra consistently are due to negative ion mass spectrum of resorcinol shows a very intense the Cn - and CnH - series.

Positive and negative ion LDI mass spectra of 1,3-dihydroxybenzene. Other prominent peaks observed 3-pyridinecarboxylic acid pyrazinecarboxamide are due to the carbon clusters Cn- and CnH-. Aliphatic Hydrocarbons and Derivatives. Long-chain 4-nitrophenol aliphatic hydrocarbons and their aldehyde, ketone, alcohol, and pentamethylbenzene 1,7,7-trimethylbicyclo[2.

Dicarboxylic acids containing trans-stilbene carbon atoms are routinely detected in airborne particles at 1,3,5-trichlorobenzene 4-hydroxy-3,5-dimethoxybenzaldehyde concentrations from to ng m-3 25,39 and are believed to be 2,4-diaminophenol dihydrochloride produced from both primary sources40 and secondary aerosol phenylbenzoate chemistry.

Figure 6 shows the positive and negative ion mass spectra of ionization since the molecule consists of only six carbon atoms. This com- R. A large peak R. Global Biogeochem. Cycles 1 9 9 0 , 4 , compound.

Total Environ. Positive and negative ion LDI mass spectra of 1,2-benzenedicarboxylic acid. In fact, some methanesulfonic acid 96 of these long-chain compounds have been detected in some recent cisbutenedioic acid diethylaminoethanol source characterization experiments,45 indicating that under butanedioic acid certain circumstances, matrix effects do in fact allow for detection oxalic acid dihydrate of these compounds in real samples.

In general, polyfunctional aliphatic compounds ionize easier and can be detected with greater sensitivity than long-chain mass spectrum contains almost no information indicative of species. Formation of protonated molecules greatly aids in the molecular composition. Even at low laser fluence, only low-mass identification of these compounds by limiting their fragmentation carbon cluster fragments are observed. In addition, typically used to identify carbonyl compounds in EI mass the information available in the negative ion mass spectra should spectrometry32 is of little diagnostic value because this series is not be overlooked, since the presence of oxygen and nitrogen in not observed above C5 in the typical nonanal spectra.

Carbon the molecule can be observed. In some cases, such as nonanal, it clusters Cn- and CnH- are observed in the negative ion mass is observed that detection and identification cannot be performed spectrum, as with all other organic compounds analyzed.

The only spectra. Organic Salts. For the other long- nitric and sulfuric acid and ammonia in the gas phase in the chain species studied 1-hexadecanol, 1-hexadecanoic acid, oleic atmosphere allows for the possible reaction of these compounds acid, docosanol, octacosane, hexadecyl hexadecanoate , no ions with existing organic compounds to form salts that can be either were detected using either positive or negative polarities, other 45 Silva, P.

This is not 46 Silva, P. Positive and negative ion LDI mass spectra of n-nonanal. Figure 7. Positive and negative ion LDI mass spectra of glycine. Four major peaks acetic acid, ammonium salt 77 methanesulfonic acid, ammonium salt are observed in the negative ion mass spectrum.

Mass-to-charge methanesulfonic acid, sodium salt 46, 62, and are nitrate-related peaks, assigned to NO 2- , triethylamine, nitrate salt NO3- , and HNO 6- , respectively. The lack of peaks due to carbon clusters in the negative ion mass spectra is striking compared to all the previous spectra.

This indicates that, for quaternary volatile or semivolatile. This illustrates the importance reactions see Table 4. These In Figure 9, the positive ion and negative mass spectra of particles were generated by reaction of diethylethanolamine with sodium methanesulfonate are displayed. Methanesulfonic acid nitric acid in the gas phase. Positive and negative ion LDI mass spectra of diethylethanolammonium nitrate.

Figure 9. Positive and negative ion LDI mass spectra of sodium methanesulfonate. Particle mass can form adduct ions. Even oxygenated PAHs such as perinaph- spectra resembling both standards ammonium and sodium thenone shown pure in Figure 3 show evidence for some proton methanesulfonate have been observed in ambient mass spectra attachment in the presence of an acid. Although the interpretation of organic compounds in single- 5. Potential Application of Results to Ambient Particles.

Being able to range of organic compounds, in addition to a full array of inorganic characterize particles simply based on functional group informa- species. This can constrain the interpretation of organic mass tion would represent a major advancement in particulate matter spectra because only one mass spectrum is acquired for a particle analysis, compared to current procedures that identify only total containing perhaps hundreds of compounds.

In addition, the organic carbon, assuming a constant amount of oxygen- and presence of certain compounds can serve as a matrix which may nitrogen-containing organic compounds.

In this case, negative change the detection characteristics of other compounds. As an ion mass spectra are extremely useful for identifying particles example, Figure 10 shows the positive and negative ion mass that contain solely hydrocarbons versus particles that include spectra of particles containing a mixture of resorcinol Figure functionalized compounds.

Although some recent work has 4 and phthalic acid Figure 5. This be desirable. Positive and negative ion LDI mass spectra of a mixture of 1,3-dihydroxybenzene and 1,2-benzenedicarboxylic acid. The tendency of negative ions to undergo disintegration, Analysis of negative ion mass spectra also has disadvantages though making molecular identification more difficult, actually aids in certain areas. Negative ion mass spectra, although helpful for in determining the presence of functional group information.

The elemental carbon EC. Previous work with LAMMA Several different oxygen-containing fragments in negative ion concluded that it is far more precise to use positive ion mass mass spectra may be used to identify particles containing oxygen- spectra for this purpose,53 where traditional fragmentation mech- ated species.

A second possible marker is the peak that occurs using data from negative ions. Although certain positive ions can also be due to the halogen species, it is impossible to discern them from indicative of oxygen species, e. These cluster Several other fragment ions in negative ion mass spectra merit ions are more typically observed with high laser fluence. Chlorine special attention.

Mass-to-charge 42 CNO - or C2H2O - is a peak and bromine can be identified on the basis of isotope ratios and observed quite often in source emissions experiments and ambient are observed from aromatic compounds with halogen functional data acquisition.

Although A number of positive ions can potentially be used to obtain this peak was observed in the negative ion mass spectrum of chemical structure information. The peak has not been observed from any other compound mass fragments are typically quite large in ion intensity.

The high- that has nitrogen and oxygen functional groups in its structure, and low-aromatic series of peaks are frequently present. However, except when an actual amide group is present. However, the presence oxygenated aromatic compounds. However, at this higher mass, of alkyl groups can be observed similar to EI mass spectrometry.

This book consists of nine chapters and begins with a historical overview of mass spectrometry and a discussion on some important developments in the field, along with a summary of interpretation objectives and methods.

The following chapters focus on instruments, ion sources, and detectors; recording of the mass spectrum and the instrumental and sample variables affecting the mass spectrum; sample introduction systems; and fragmentation reactions. Correlations as applied to interpretations are also considered, with emphasis on applications of the branching rule as well as beta-bond and alpha-bond cleavages.

Example interpretations, calculations, data-processing procedures, and computer programs are included. This monograph is intended for organic chemists, biochemists, mass spectroscopists, technicians, managers, and others concerned with the whys and wherefores of mass spectrometry.

Preface Acknowledgments Chapter 1 Introduction I. Scope and Definition II. Historical Developments III. Selection of Instrumentation V. Introduction II. Ion Sources III. Definitions II. Types of Ions Observed VI. Techniques of Sample Introduction IV. Separation Techniques V. Misinterpretation Associated with the Sample VI.

The Ionization Process II. General Principles of Fragmentation V. Analytical Objectives II. Miscellaneous Objectives III.