Mar 27, 2015 mass spectrometry mass spectrometry is the most accurate method for determining the molecular mass of the compound and its elemental composition. Ring compounds usually contain peaks at the mass number characteristic of the ring e. 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. Page 1 of 38 fragmentation pathways of drugs of abuse and their metabolites based on qtof msms and mse accuratemass spectra 5 lubertus bijlsma a, juan v. A simplified simulation of mass spectra and simulation of fragmentation pattern is only possible for certain molecule classes. The molecular ion containing the 35 cl isotope has a relative formula mass of 78.
Mass spectrometry and free radicals really radical cations when an organic molecule is ionized in an ms instrument, especially by ei, it generates a radical cation. Comparative study on the fragmentation of some simple. Major fragmentation pattern is alhpa cleavage resulting in loss of sidechain and formation of acylium inon. Alternative mass spectrometry techniques for the validation. Four decades of structure determination by mass spectrometry. Fragment peaks other than the molecular ion peak is. Handy dandy guide to mass specral fragmentation patterns. Molecular ion peaks are present, possibly with low intensity. Mass spectrometry fragmentation patterns chemistry. These reactions are well documented over the decades and fragmentation pattern is useful to determine the molar. The relative intensity of the molecular ion peak is greatest fro the straight chain compound and decreases as the degree of branching. Mass spectroscopy ppt mass spectrometry time of flight. Introduction mass spectrometry mass spec or ms uses high energy electrons to break a molecule into fragmentation.
The fragmentation pattern contains clusters of peaks 14 mass units apart which represent loss of ch2nch3. Us20120286156a1 selective ion mobility spectrometer. Double bonds favor cleavage beta to the double bond. Chapter 2 fragmentation and interpretation of spectra 2. The separation chamber of the mass spectrometer is keep under a high vacuum and so all. Ion formed by addition or the removal of one or several electrons to or from the sample moleculeselectron impact eims. The nature of the fragments often provides a clue to the molecular structure, but if the molecular ion has a lifetime of less than a few microseconds it will not survive long enough to be observed.
It is also called as positive ion spectra or line spectra. Pdf mass fragmentation pattern of new zygophyllosides. The leading scientist in this field was fred mclafferty who together with frantisek turecek has written a very famous text book. Mass fragmentation pattern of z25arylpyrazol3 yl 3arylacrylonitriles article pdf available in indian journal of chemistry section b 39b12. Gas chromatography mass spectroscopy introduction gas chromatography mass spectroscopy gcms is one of the socalled hyphenated analytical techniques. Introduction to ionization and fragmentation in mass spectrometry. Indeed, mass spectrometry appears to be regarded as a mysterious method, just good enough to supply some molecular weight information. Mass spectrometry is particularly important to organic chemistry because it allows acquisition. The one containing 37 cl has a relative formula mass of 80 hence the two lines at mz 78 and mz 80 notice that the peak heights are in the ratio of 3. Mass spectroscopy minnesota state university moorhead. Fragmentation produces distinct pattern of fragment peaks at different masstocharge ratios mzs that can be used to annotate chemical structures 7, 8. Lecture notes in eimass spectrometry by torben lund.
Four new saponins were isolated from the whole plant of zygophyllum propinquum decne and purified by column chromatography and reverse phase high performance liquid chromatography hplc and analyzed by fast atom bombardment mass. Handydandy guide to mass spectral fragmentation patterns. Save as pdf interpreting a mass spectrum mass spectroscopy. By adding known quantities of deuterated ca eine to our samples, extracting all. Feb 10, 20 in most cases, the nascent molecular ion of the analyte produced fragment ions by cleavage of the bond and the resulting fragmentation pattern constitutes the mass spectrum. Mass spec fragmentation an extremely useful result of ei ionization in particular is a phenomenon known as fragmentation. Series ch3 o h3c o o o ch3 o o 3 o o o 3 o h h n n ch3 o h3c o o o ch3 o o o 2 h ho ch3 o h n. Pdf s available in description find your topic and download the pdf dsc dta tga thermoanalytical techn. Insilico optimisation of mass spectrometry fragmentation. R1 c o r2 c o r1 c o r2 c o and o r1 x esters, acids, amides. For the analytical chemist, a mass spectrum is useful for two applications. Mass spectrometry and free radicals rutgers university. Mass spectrometry liskeard school and community college. Secondary fragmentation processes involving ions me 198, 171, 167, 166, 154, 140 and 9 have been clarified.
Ion fragmentation of small molecules in mass spectrometry. Works only for peptides, lipids, oligosaccharides, alkanes. In mass spectrometry, fragmentation is the dissociation of energetically unstable molecular ions formed from passing the molecules in the ionization chamber of a mass spectrometer. As the name implies, it is actually two techniques that are combined to form a single method of analyzing mixtures of chemicals. The mass to charge ratio mz is used to describe ions observed in mass spectrometry. Feb 19, 2015 introduction to ionization and fragmentation in mass spectrometry. Major fragmentation pattern is alhpa cleavage resulting in loss of sidechain and formation of acylium inon also mclafferty rearrangement where possible. Data system mass detector analyzer vacuum system source inlet region more precisely mass spectrometry determines the mass of a molecule. Saturated rings lose side chains at the alpha carbon. Primary amides show a base peak due to the mclafferty rearrangement. Wesener, bayer industry services, leverkusen chemical ionization, j. Does not work with complex side chain modifications machine learning methods for simulation and prediction of mass. Electron impact induced fragmentation patterns of simple phenothiazines have been reinvestigated using metastable ion studies, exact mass measurements and deuterated derivatives.
In most cases, the nascent molecular ion of the analyte produced fragment ions by cleavage of the bond and the resulting fragmentation pattern constitutes the mass spectrum. Fragmentation patterns virtual mass spectrometry laboratory. This is considering a solid bar to help the explanation of fragmentation pattern of pc and pg to elucidate the course of the chemical change. Veith, technical university of darmstadt field desorption, r. Fragmentation pattern and its rules and interpretation of mass spectroscopy guided by.
Pdf mass fragmentation pattern of z25arylpyrazol3yl. Proposed fragmentation pathway associated to the msms results in figure 7. Fragmentation pathways of drugs of abuse and their metabolites based on qtof msms and mse accuratemass spectra 5 lubertus bijlsma a, juan v. In order to better understand microplastic fragmentation we proceeded to a thorough physicochemical characterization of samples. Monoisotopic mass is typically expressed in unified atomic. Fragmentation pathways and structural characterization of 14. Buy introduction to spectroscopy, international edition 4 by appendix 9. Mass spectrometry fragmentation patterns chemistry libretexts. Lecture 3 mass spectrometry principles of mass spectrometry mass spectrometry separates molecules based on the mass to charge ratio. This study provides a new alternative to validate mechanisms of fragmentation of important natural products. These reactions are well documented over the decades and fragmentation pattern is useful to. Understanding the fragmentation pattern of marine plastic. Assistant professor department of pharmaceuticcal chemistry dharmaj degree pharmacy college presented by.
The fragments of a molecule cause a unique pattern in the mass spectrum. The global estimation of microplastic afloat in the ocean is only approximately 1% of annual global plastic inputs. Niessen b a research institute for pesticides and water, university jaume i, castellon, spain. Mass spectroscopy ppt free download as powerpoint presentation. Examine spectrum for peak clusters of characteristic isotopic patterns.
This reflects fundamental knowledge gaps in the transformation, fragmentation, and fates of microplastics in the ocean. This content was copied from view the original, and get the alreadycompleted solution here. Caprioli, vanderbilt university, nashville fast atom bombardment. The choice of fragmentation strategy, which determines how precursor ions are selected for further fragmentation in tandem mass spectrometry. The peak corresponding to the loss of two ring atoms is much larger than for the loss of one ring atom. The mass spectrum allows an experienced analyst to identify the compound or at a. The ionized molecule often fragments into smaller ionsradicals. The mass spectrum that is produced is characteristic of that particular sample. This pattern results in the familiar grouping of fragments spaced 14 units apart with the largest fragment in the cluster resulting from the cnh 2n1 o 2 ion figure 6. The fragmentation pattern which results is reproducible, allowing these patterns to be used as an identifying fingerprint. Fragmentation pathways and structural characterization of.
For small numbers of unknown compounds, these patterns can be visually matched, though libraries of patterns can be searched by computer for more complex problems, with the best matches being returned by the software. Mass spectra give characteristic isotope patterns according to mass and natural abundance. Fragmentation pathway of drugs of abuse and their metabolites. The atomic charges of atoms are found to be good predictors of the fragmentation pathways. Fragmentation mechanisms in electron impact mass spectrometry. Mass spectrometry mass spectrometry is the most accurate method for determining the molecular mass of the compound and its elemental composition.
It is important to compare mass spectral fragmentation pattern of phenol as parent molecule fig. Mass spectral fragmentation patterns of heterocycles. Mass spectroscopy mass spectroscopy is a technique causing the formation of the gaseous ions with or without fragmentation. The electron ionization ei mass spectra of tropane derivatives were first studied by budzikiewicz, djerassi, and cowork. Metzger, university of oldenburg electron ionization and fragmentation of organic ions and interpretation of ei mass spectra, j. Gas chromatographymass spectroscopy gcms is one of the socalled hyphenated analytical techniques. A common validated ei fragmentation pattern for both capsaicin and dihydrocapsaicin was established using appropriated mass spectrometric methods together with convenient hydrogendeuterium labeling.
Gas chromatography separates the components of a mixture and. When non mass spectrometrists are talking about mass spectrometry it rather often sounds as if they were telling a story out of poes tales of mystery and imagination. When interpreting fragmentation patterns, you may find it helpful to know that, as you might expect, the weakest carboncarbon bonds are the ones most likely to break. The radical cation that is produced when an electron is knocked out of a neutral closedshell molecule in eims initially possesses a lot of energy. The mass peaks provide the information that enables identification of the sample from the molecular ion peak and from the characteristic fragmentation pattern. Fragmentation produces distinct pattern of fragment peaks at different mass tocharge ratios mzs that can be used to annotate chemical structures 7, 8. The mass spectrometry of a number of 6substituted coumarins was studied in the context of correlating fragmentation pathways and electronic charges of atoms performed by am 1 semiempirical method. Fragmentation patterns the fragmentation of molecular ions into an assortment of fragment ions is a mixed blessing. A split producing a tertiary carbocation will be more successful still. Cad fragmentation patterns for v analogs through the two pathways we propose are consistent with those previously proposed by bell et al. Fragmentation patterns in mass spectra chemistry libretexts. Thus, the mass spectrum of each compound is unique and can be used as a chemical fingerprint to characterize the sample.
228 168 642 399 938 274 667 695 1260 752 225 132 321 213 1015 97 387 1338 117 467 581 1188 1140 1308 242 871 789 688 1535 497 1263 791 1198 1153 721 633 1050 244 26 721 730