Typical fragmentation patterns part 6 of 7 owen priest. Additional analysis if no inferences are realistic from tables 3 and 4, attempt deeper analysis of the mass spectrum. So far, weve looked at how chemists can determine the presence of particular bonds present in molecules with infrared spectroscopy, and how they can gain information about the structure of molecules using hydrogen and carbon nuclear magnetic resonance. Van deemter jj, zuiderweg fj and klinkenberg a 1956. The basic aspect of organic mass spectrometry consist of bombarding the vapour of an organic compound with a beam of energetic electron accelarated from a filament to an energy of 70 ev to form positively charged ions molecular ions. A radical cation is a cation with an unpaired electron. Wesener, bayer industry services, leverkusen chemical ionization, j. In the mass spectrum, the heaviest ion the one with the greatest mz value is likely to be the molecular ion. Download pdf interpretation of mass spectra, by fred w. It also states the importance of metastable ions in mass spec analysis. The mass to charge ratio mz is used to describe ions observed in mass spectrometry. Frantisek tureek and a great selection of related books, art and collectibles available now at. Which requires at least one gamma hydrogen and one site for radical cation generation. Buy interpretation of mass spectra 1993 by mclafferty, fred w.
Chad presents the common fragmentation patterns for ketones and aldehydes alpha cleavage and the mclafferty rearrangement. The ionized molecule often fragments into smaller ionsradicals. The three essential functions of a mass spectrometer, and the associated components, are. Apr 20, 2017 mclafferty rearrangement is the most important fragmentation reaction observed in the mass spectrometry. Use ms workbook suite to create fully searchable, live dbs of mass spectra, chromatograms, and uv spectra together with structure assignments, annotations, and other associated data. The mass spectra of simple hydrocarbons have peaks at mz values corresponding to the ions produced by breaking cc bonds. Mass spectrometry and interpreting mass spectra compound. Here a fully automated computer algorithm is applied to complex mass spectra of peptides and proteins. A basic approach, second edition combines coverage of the principles underlying mass spectral analysis with clear guidelines on how to apply them in a laboratory setting. Mclafferty s most popular book is interpretation of mass spectra. Mass spectrometry of organic ions covers the underlying theories and major applications of mass spectrometry. Turecek published by university science books, mill valley, 1993 isbn 0. This is caused by a different ion than the corresponding peak in the pentane mass spectrum.
In order to interpret the mass spectrum, one should attain an understanding of the ionisation process. The molecular weight of a pure compound from the identification of the parent peak. Gas chromatographymass spectrometry gc ms interpretation of ei spectra jeremy keirsey ccic msp. At its simplest, mass spectrometry gives information about the atomic or molecular weight. The most famous rearrangement is called the mclafferty rearrangement. It is commonly used for the identification of organic compounds from electron ionization mass spectrometry. It is also called as positive ion spectra or line spectra. In a number of spectra, no molecular ion can be found, because the molecular ion is usually very unstable and decomposes into fragment ions before it can reach the detector.
Octane is a saturated straight chain therefore the spectra is characterized via clusters of peaks 14 mass units ch 2 groups apart, as successive cc bonds all along the chain are cleaved in various molecules. Interpretation of mass spectra, 4th edition, by fred mclafferty, published by university science books, 0935702253. Fred was a pioneer in the early environmental movement, and is famous for his books on interpretation of mass spectra, which are still used in university courses and acs courses for the. Interpretation of mass spectra, say the authors, aims at correlating ion dissociation mechanisms on a much broader scale, with emphasis on basic attributes such as ionization energies, proton affinities, and bond dissociation energies. For the analytical chemist, a mass spectrum is useful for two applications. Veith, technical university of darmstadt field desorption, r. Using the molecular ion to find the relative formula mass. Common fragmentation processes for organic molecules are the mclafferty rearrangement and alpha cleavage. For the fourth in the analytical chemistry series, we turn to mass spectrometry. A few compounds have mass spectra which dont contain a molecular ion peak, because all the molecular ions break into fragments. The fundamental concepts of ionization, fragmentation, and rearrangement of ions as found in mass spectra are covered in some detail, along with the. Isotopic percentage and nominal mass calculation are also. Secure interpretation of the mass spectra requires an adequate understanding of the mechanism of the key fragmentation processes of steroids and the present paper summarizes recent work from the authors laboratory dealing with the elucidation of the fragmentation.
Interpretation of mass spectra of organic compounds. Mass spectrometry mass spectrometry is the most accurate method for determining the molecular mass of the compound and its elemental composition. A mass spectrum is the plot of relative abundance of ions against their mass charge ratio. Interpretation of mass spectra, fourth edition by fred w. By convention, m is the numerical value for the mass of the ion and z is the numerical value for the charge of the ion. Fragmentation reactions spectrum interpretation confirmation of ion structural assignment biomolecule dissociation l. The following chapter introduces one of the key disciplines of organic mass spectrometry. Mclafferty has 16 books on goodreads with 27 ratings. Interpretation of mass spectral data 1 the molecular ion the molecular ion in an e.
Mclafferty, frantisek tureek extensively revised and updated, this new edition, as in previous editions, emphasizes the point that the most important part of learning how to interpret unknown mass spectra is to practice interpreting mass spectra. This is the site that will give you reduce of searching book interpretation of mass spectra, by fred w. Automated reduction and interpretation of springerlink. Finally, it discusses the mclafferty rearrangement which occurs following the. Extensively revised and updated, this new edition, as in pr. Longitudinal diffusion and resistance to mass transfer as causes of non ideality in chromatography.
Reactive tandem ion mobility spectrometry with electric field fragmentation of alcohols at ambient pressure. If good inferences could be made, use the remainder of the mass spectrum to try to elucidate structural features or isomerism. Nitrogen rule in mass spectrometry, interpretation of mass spectrum. Interpretation of ms ms m ass spectra of drugs and pesticides wilfried m. Interpretation of a mass spectrum, chemistry tutorial.
The leading scientist in this field was fred mclafferty who together with frantisek turecek has written a very famous text book. Extensively revised and updated, this new edition, as in previous editions, emphasizes the point that the most important part of learning how to interpret unknown. Interpretation of msms mass spectra of drugs and pesticides. The mass spectrometer in order to measure the characteristics of individual molecules, a mass spectrometer converts them to ions so that they can be moved about and manipulated by external electric and magnetic fields. Click and collect from your local waterstones or get free uk delivery on orders over.
Mclafferty, frantisek tureek is a very helpful interest and doing that can be undergone at any time. Effectively share knowledge across organizations by not only capturing data, but also analytical interpretations, including relationships between spectra and. As youve seen, the mass spectrum of even very similar organic compounds will be quite different because of the different fragmentations that can occur. Examples of fragmentation and the interpretation of mass spectra. Buy interpretation of mass spectra, fourth edition by fred w. Chapter 2 fragmentation and interpretation of spectra 2. At high energies, the ionising electron beam can fragment the molecule by cleaving particular bonds. Interpretation of mass spectra paperback january 1, 1966 by fred w. This organic chemistry video tutorial provides a basic introduction into mass spectrometry. Fragmentation of organic ions and interpretation of ei mass. Get your kindle here, or download a free kindle reading app.
It is sometimes found that a molecule containing a ketogroup undergoes. Mclaffertys most popular book is interpretation of mass spectra. The chapter includes an introduction to the main ionisation techniques in mass spectrometry and the way the resulting fragments can be analysed. Everyday low prices and free delivery on eligible orders. Flock for their efforts and to the staff of the local libraries for their friendly support.
Mass spectrometry of natural products sciencedirect. Caprioli, vanderbilt university, nashville fast atom bombardment. The unified atomic mass u and the elementary charge units e are used for these values. This method uses a subtractive peak finding routine to locate possible isotopic clusters in the spectrum, subjecting these to a combination of the previous fourier transform patterson method for primary charge determination and the method for leastsquares fitting to a theoretically. Mclafferty rearrangement mass spectrometry youtube. Feb 01, 2016 for the love of physics walter lewin may 16, 2011 duration. Lecture notes in eimass spectrometry by torben lund. Mclafferty, frantisek turecek from waterstones today.
Pdf download interpretation of mass spectra, by fred w. First, the fundamental notions of mass spectrometry are explained, so that the reader can easily cover this chapter graphs, main pick, molecular ion, illogical pick, nitrogen rule, etc. Looks at the major fragmentation mechanisms of the mass spec molecular ion. My thanks are extended to the staff of my facility n. Interpretation of mass spectra of organic compounds outlines the basic instrumentation, sample handling techniques, and procedures used in the interpretation of mass spectra of organic compounds. Data system mass detector analyzer vacuum system source inlet region more precisely mass spectrometry determines the mass of a molecule. The characteristic peak occurs due to common mclafferty rearrangement, with cleavage of a. Conventionally in mass spectrometry, we calculate the molecular weight using the masses. Mass spectra is a plot of relative abundance against mass tocharge ratio. Provided you have a computer data base of mass spectra, any unkown spectrum can be computer analysed and simply matched against the data base.
Sauerwein to use a large set of electron ionization mass spectra from the nistepanih mass spectral library is also gratefully acknowledged. They stress that the most important part of learning how to interpret unknown mass spectra is to practise doing it. Mass spectral interpretation is the method employed to identify the chemical formula, characteristic fragment patterns and possible fragment ions from the mass spectra. The masses of peaks 1, 2, 3, and 4 are successively smaller in mass by one. It explains how to match the correct molecular fragments with the corresponding mz peaks in the mass. Metzger, university of oldenburg electron ionization and fragmentation of organic ions and interpretation of ei mass spectra, j. Mclafferty s text has become a classic for classroom or self study concerned with interpreting mass spectra in order to discern molecular structures or identities of compounds. Mass spectrometry is used in organic chemistry, but this isnt in the organic. The molecular fragmentation peaks in the mass spectrum can give clues as to the substructure of the molecule. After molecules are ionized in a mass spectrometer, they become radical cations that can then be sorted and weighed.
It is commonly used for the identification of organic compounds from electron ionization mass. The book flows in a very understandable way, and it is fairly inexpensive for the imformation provided. Fragmentation of organic ions and interpretation of ei. In addition to forming molecular ions, organic molecules decompose into fragment ions in a mass spectrometer. Interpretation of mass spectral data 1 the molecular ion. Mass spectrometry ms is an analytical technique that produces. This method uses a subtractive peak finding routine to locate possible isotopic clusters in the spectrum, subjecting these to a combination of the previous fourier transform patterson method for primary charge determination and the method for leastsquares fitting to a theoretically derived.
Mass spectrometry plays a crucial role in the structure elucidation of new sterols, notably those of marine origin. Expert mass spectrometry software acdms workbook suite. Gaschromatographymass spectrometry gc ms interpretation. Works full mechanism of inductiveheterolytic cleaveage. Mass spectroscopy mass spectroscopy is a technique causing the formation of the gaseous ions with or without fragmentation. Buy a cheap copy of interpretation of mass spectra 3ed. Mass spectroscopy minnesota state university moorhead. Mass spectrum interpretation fragmentation reactions 1.
The mass spectrum intro the first time i saw electrospray data a personal storythe focus of this tutorialthis tutorial mainly focuses on the interpretation of mass spectra containing multiply charged molecules generated by the electrospray ionization process. Mass spectrometry mclafferty rearrangement problems asked in previous 5 csir exams duration. The mclafferty rearrangement is a reaction observed in mass spectrometry during the fragmentation or dissociation of organic molecules. Mclafferty rearrangement is the most important fragmentation reaction observed in the mass spectrometry. Which requires at least one gamma hydrogen and one.
This chapter book starts with a survey of the mechanisms by which organic ions can decompose and rearrange, as well as the generalized concept in terms of physicalorganic chemistry. Mclafferty author see all 7 formats and editions hide other formats and editions. A mass spectrum can represent many different types of information based on the type of mass spectrometer and the specific experiment applied. Some of these radical cations can also rearrange after being ionized.
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