Mass Spectral Fragmentation Behavior Research Articles

Systematic identification of compounds in Macleaya microcarpa by high-performance liquid chromatography/quadrupole time-of-flight tandem mass spectrometry combined with mass spectral fragmentation behavior of Macleaya alkaloids.

Macleaya microcarpa (Maxim.) Fedde belongs to the genus Macleaya of the Papaveraceae family. Benzylisoquinoline alkaloids (BIAs) are considered the main bioactive constituents of M. microcarpa. Using high-performance liquid chromatography/quadrupole time-of-flight tandem mass spectrometry (HPLC/QTOFMS/MS) we identified BIAs in the aerial parts of M. microcarpa in the early flowering stage. Target profiling and identification of BIAs in the extracted samples from the fresh aerial parts of M. microcarpa were exclusively based on a personal, accurate, mass database of known compounds and the mass spectral fragmentation behavior of Macleaya alkaloids. A total of 97 alkaloids, comprising 7 benzyltetrahydroisoquinolines, 1aporphine, 9 tetraprotoberberines, 3 protoberberines, 2 N-methyltetrahydroprotoberberines, 4 protopines, 47 dihydrobenzophenanthridines, and 24 benzophenanthridines, were identified from the fresh aerial parts of M. microcarpa, and 77 of these were detected for the first time in M. microcarpa. In addition, some of the screened alkaloids were related to the biosynthetic pathways of sanguinarine and chelerythrine. The integrated method is sensitive and reliable for screening and identifying trace or ultra-trace isoquinoline alkaloids and has contributed to a better understanding of BIAs in the fresh aerial parts of M. microcarpa.

Feruloyl dopamine-O-hexosides are efficient marker compounds as orthogonal validation for authentication of black cohosh (Actaea racemosa)-an UHPLC-HRAM-MS chemometrics study.

Due to the complexity and variation of the chemical constituents in authentic black cohosh (Actaea racemosa) and its potential adulterant species, an accurate and feasible method for black cohosh authentication is not easy. A high-resolution accurate mass (HRAM) LC-MS fingerprinting method combined with chemometric approach was employed to discover new marker compounds. Seven hydroxycinnamic acid amide (HCAA) glycosides are proposed as potential marker compounds for differentiation of black cohosh from related species, including two Asian species (A. foetida, A. dahurica) and two American species (A. pachypoda, A. podocarpa). These markers were putatively identified by comparing their mass spectral fragmentation behavior with those of their authentic aglycone compounds and phytochemistry reports. Two isomers of feruloyl methyldopamine 4-O-hexoside ([M + H]+ 506) and one feruloyl tyramine 4-O-hexoside ([M + H]+ 476) contributed significantly to the separation of Asian species in principle component analysis (PCA) score plot. The efficacy of the models built on four reasonable combinations of these markers in differentiating black cohosh and its adulterants were evaluated and validated by partial least-square discriminant analysis (PLS-DA). Two models based on these reduced dataset achieved 100% accuracy based on the current sample collection, including the model that used only three feruloyl dopamine-O-hexoside isomers ([M + H]+ 492) and one feruloyl dopamine-O-dihexoside ([M + H-hexosyl]+ at m/z 492). Graphical abstract Hydroxycinnamic acid amide glycosides are proposed as potential marker compounds for authentication of black cohosh.

Profiling and characterisation by liquid chromatography/multi-stage mass spectrometry of the chlorogenic acids in Gardeniae Fructus

The chlorogenic acids of Gardeniae Fructus used traditionally as a Chinese herbal medicine (zhizi) have been investigated qualitatively by liquid chromatography/multi-stage mass spectrometry (LC/MS(4)). Twenty-nine chlorogenic acids were detected and twenty-five characterised to regioisomer level on the basis of their fragmentation, twenty-four for the first time from this source. Assignment to the level of individual regioisomers was possible for three caffeoylquinic acids, three dicaffeoylquinic acids, three sinapoylquinic acids, four caffeoyl-sinapoylquinic acids, two feruloyl-sinapoylquinic acids, one p-coumaroyl-sinapoylquinic acid, three (3-hydroxy, 3-methyl)glutaroylquinic acids, two (3-hydroxy, 3-methyl)glutaroyl-feruloylquinic acids, one (3-hydroxy, 3-methyl)glutaroyl-dicaffeoylquinic acid, and one (3-hydroxy, 3-methyl)glutaroyl-caffeoyl-feruloylquinic acid. Six (3-hydroxy, 3-methyl)glutaroyl-caffeoylquinic acids were detected and two were tentatively assigned as 3-caffeoyl-4-(3-hydroxy, 3-methyl)glutaroylquinic acid and 3-caffeoyl-5-(3-hydroxy, 3-methyl)glutaroylquinic acid. The (3-hydroxy, 3-methyl)glutaroyl residue modifies the mass spectral fragmentation behavior and elution sequence compared with the chlorogenic acids that contain only a cinnamic acid residue(s). Fourteen of these twenty-nine chlorogenic acids have not previously been reported from any source.

Systematic screening and characterization of tertiary and quaternary alkaloids from corydalis yanhusuoW.T. Wang using ultra-performance liquid chromatography–quadrupole-time-of-flight mass spectrometry

Ultra-performance liquid chromatography–quadrupole-time-of-flight mass spectrometry (UPLC–Q-TOF-MS) is an effective technique for analysis of complex samples with offering rapid, efficient separation in combination with accurate mass measurement and tandem mass spectrometry (MS/MS). This paper exploits this technique to identify the alkaloids in corydalis yanhusuo, an important antalgic Traditional Chinese Medicine (TCM). The mass spectral fragmentation behavior of one tertiary alkaloid and two quaternary alkaloids was studied in detail. Low-abundance product ions of tertiary and quaternary alkaloids were investigated and compared between each other. Sixteen alkaloids were screened out by using a systematic screening method developed in our laboratory; structures of eight therein were identified by characteristic UV absorption spectrum and positive ion mode of Q-TOF-MS/MS; and two of them were discovered for the first time in corydalis yanhusuo to our knowledge. This research demonstrates the potential of UPLC-Q-TOF-MS in structural characterization and identification of components in traditional Chinese herbal medicines.

Identification and Structural Elucidation of Vitamin D3 Metabolites in Human Urine Using LC-MS-MS

An analytical method was developed for the identification of primary vitamin D3 metabolites in human urine using liquid chromatography tandem mass spectrometry in positive mode. Urine samples were purified using C18 solid-phase extraction cartridges and analytical separations were performed by reversed phase liquid chromatography in gradient mode using ammonium acetate (0.01 mol L−1) and acetonitrile as the mobile phases. Identification and structural elucidation of the metabolites were carried out by comparison with mass spectral fragmentation behavior of vitamin D3 and retention characteristics. Three primary urinary vitamin D3 metabolites were identified as 25-hydroxyvitamin D3, 1α,25-dihydroxyvitamin D3 and vitamin D3 sulphate, respectively.

Structural characterization of iridoid glucosides by ultra‐performance liquid chromatography/electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry

The mass spectral fragmentation behavior of ten iridoid glucosides (IGs) has been studied using electrospray ionization (ESI), collision-induced dissociation (CID), and quadrupole time-of-flight tandem mass spectrometry (Q-TOF MS/MS). In the negative ESI mass spectra, the deprotonated [M-H](-) ion was observed for all of the ten IGs except gardoside methyl ester, while the formate adduct [M+HCOO](-) ion appeared to be favored by the presence of a methyl ester or a lactone group in the C-4 position when formic acid was added to the mobile phase. The CID MS/MS spectra of the [M-H](-) ions have been used for structural elucidation. Ring cleavages of the aglycone moiety have been observed in the MS/MS spectra, corresponding to (1,4)F(-), (2,6)F(-), (2,7)F(-), and (2,7)F(0) (-) ions, based on accurate mass measurements and the elemental compositions of the product ions. These characteristic ions gave valuable information on the basic structural skeletons. Furthermore, on the basis of the relative abundances of the fragment ions (1,4)F(-) and (2,7)F(-), different sub-classes, such as cyclopentane-type and 7,8-cyclopentene-type IGs, can be differentiated. Ring cleavage of the sugar moieties was also observed, yielding useful information for their characterization. In addition, the neutral losses, such as H(2)O, CO(2), CH(3)OH, CH(3)COOH, and glucosidic units, have proved useful for confirming the presence of functional substituents in the structures of the IGs. Based on the fragmentation patterns of these standard IGs, twelve IGs have been characterized in an extract of Hedyotis diffusa Willd. by means of ultra-performance liquid chromatography/Q-TOF MS/MS, of which six have been unambiguously identified and the other six have been tentatively identified.

Determination of Oleanolic, Betulinic and Ursolic Acid in Lamiaceae and Mass Spectral Fragmentation of Their Trimethylsilylated Derivatives

Phytochemical investigations of different species of Lamiaceae family (rosemary-Rosmarinus officinalis L., sage-Salvia officinalis L., winter savory-Satureja montana L., clary sage-Salvia sclarea L. and sticky sage-Salvia glutinosa L.), using gas chromatography and mass spectrometry (GC-MS) were performed. The studies were focused on oleanolic, betulinic and ursolic acid. Since oleanolic and ursolic acid are position isomers with very similar structures, the difficulties in their separation and identification have been reported by several authors. However, both compounds can be well distinguished by order of elution during gas chromatography and by intensities of the fragment ion signals in their mass spectra, where the retro-Diels-Alder reaction was primarily observed. A combination of ultrasonic extraction, solid phase extraction, size exclusion chromatography, trimethylsilylation, and GC-MS resulted in simultaneous separation, identification and quantification of the mentioned compounds. The compounds have been identified by retention time and comparison of mass spectra with those of pure standards. The mass spectral fragmentation behavior of all three derivatised acids was investigated. The obtained characteristic fragment patterns are discussed in the presented work. Good linearity over the concentration range 1–50 mg L−1 for all three compounds was confirmed. The correlation coefficients (r 2 ) were in the range of 0.9980–0.9983. Quantitative analyses of different Lamiaceae extracts showed that the oleanolic acid content ranged from 0.09 to 0.9% dry weight, content of betulinic acid ranged from traces to 0.6%, and that of ursolic acid varied from 0.09 to 1.6% dry weight.

Microwave Catalyzed Reaction of H-Dimethylphosphonate with N-(2,3-Epoxypropyl)Phthmide

Microwave catalyzed reaction of N-(2,3-epoxypropyl)phthalimide with H-dimethylphosphonate for 4 min yielded via free radical processes: trimethylphosphonate, trimethylphosphate, N-(2-propenyl)phthalimide, 2-(N-phthalimidopropyl) dimethylphosphinates, hydrogen 3-(N-phthalimidopropyl) methylphosphine oxide, hydrogen 3-(N-phthalimidopropyl)methylphosphinate, 2-(N-phthalimidopropyl) dimethylphosphonate, and 2-(N-phthalimidopropyl) dimethyl-phosph-inate. The mechanism of formation of the various compounds along with their mass spectral fragmentation behavior is described in this communication.

FORMATION AND GC-MS CHARACTERIZATION OF UNUSUAL CYCLIC SULFIDES

connection with another project involving the cleavage of the thiirane ring of cyclohexene episulfide in the presence of trifluoromethylthiocopper, the presence of several unusual cyclic sulfides (5–10, Fig. 1) was observed both in the reaction product and the starting material itself. The formation of these compounds has been rationalized on the presence and participation of the thiyl radical species. Details pertaining to their formation and characterization based on their mass spectral fragmentation behavior are presented in this communication.

Reaction of ethynylcyclopentanol with trifluoromethylsulfenyl chloride

Based on the mass spectral fragmentation behavior of the reaction products, the free radical reaction of 1-ethynyl-1-cyclopentanol ( 1) with trifluoromethylsulfenyl chloride ( 2) has been found to furnish 13 compounds formed from addition and elimination reactions. Two compounds are noteworthy in that one does not have the side chain, while the other carries an extended `tri-ynyl' side chain. This paper presents the mechanism of formation of the various compounds and their GC-MS characterization.

SYNTHESIS AND MASS SPECTRAL CHARACTERIZATION OF DIISOPROPYLAMINO-ETHANETHIOL, -SULFIDES AND -DISULFIDES AND VINYL SULFIDES

The sulfur containing chemical agent, O-ethyl-S-2-(diisopropylaminoethyl) methylphospho-nothiolate (VX), is an extremely potent inhibitor of the enzyme acetylcholinesterase and exhibits extended neurological effects. It undergoes degradation on standing alone or in the environment. Hence, identification of its primary degradation products assumes considerable importance. The synthesis and mass spectral fragmentation behavior of the title compounds, some of which are present in the VX degradation products, has not received much attention. This communication describes the synthesis and mass spectral characterization of the title compounds.

Reactions of trifluoromethylthiocopper with halomethanes

The reaction of trifluoromethylthiocopper with halomethanes, namely di- and triiodo-, dibromodichloro-, dibromochlorofluoro-, dibromo-difluoro-,bromochlorofluoro-, phenyltrichloro-, bromocyano- and dibromofluoro-methanes, has been investigated in detail. In addition to the expected compounds, the formation of unusual products such as bis(trifluoromethyl)trithiocarbonate, dimethyl(trifluoromethylthio)benzene, bis(trifluoromethylthio)fluoromethane, (trifluoromethylthio)carbonyl fluoride, carbon disulfide, carbon tetrachloride, trifluoromethylthio- benzoate, etc. was observed. In some cases, bis(trifluoromethylthio)mercury has been used instead of trifluoromethylthiocopper. The mechanism of formation of the various products and their mass spectral fragmentation behavior are described.

Synthesis and biological screening of trifluoromethylthioarsenicals

The title compounds have been prepared from the reaction of trifluoromethylthiocopper and alkyl mono- and di-haloarsines. This communication describes their synthesis, biological screening and mass spectral fragmentation behavior.

Isobutane and Ammonia Chemical Ionization Mass Spectrometry of Sesquiterpene Alcohols (MW 222)

ABSTRACT The mass spectral fragmentation behavior of 21 sesquiterpene alcohols (C 15H26O; MW 222) under the conditions of chemical ionization (CI) is investigated using isobutane and ammonia, respectively, as the reagent gases. The isobutane spectra show intense fragment ions [M + H—H2O]+ for all substances. The tendency to forming further fragment ions is different for the various compounds. This behavior reveals structural characteristics to a certain degree. Only three compounds display quasimolecular ions [M + H]+with relative intensities > 10%. Therefore, isobutane is not well suited to confirm the molecular mass and classification of this compound group is not unambiguous. With ammonia a typical set of ions is formed: [M + H—H2O]+, [M + NH4—H2O]+, [M + NH4]+ and [M + NH3· NH4]+, respectively. These ions enable to confirm the molecular mass and to classify this compound group. With the use of both the reagent gases, the identity of individual substances can be confirmed by their specific ion and inte...

THE MASS SPECTRAL FRAGMENTATION BEHAVIOR OF PYRIDINE CARBOXYLIC AND THIOCARBOXYLIC ACID ESTERS

Abstract The mass spectral fragmentation behavior of pyridine carboxylic acid and thioacid methyl esters shows several peculiarities not observed with other aromatic esters, viz., i.a., (a) COOCH3 groups in α-position are involved in rearrangement processes under participation of N; (b) neighboring COOCH3 groups fragment by ortho-effects; (c) COSCH3, CSOCH3 and CSSCH3 groups suffer complex rearrangements leading to, e.g. loss of CO, CH2CO or S2 from M+, especially when located in α-position.

Massenspektrometrie und ihre Anwendung auf strukturelle und stereochemische Probleme CLXVII Langkettige Wasserstoffverschiebung in der Massenspektrometrie

AbstractThe mass spectral fragmentation behavior of various α‐substituted tetrahydrofuran derivatives and their deuterium labeled analogs has been examined. It was established that the ester and hydroxy derivatives undergo ring fragmentation associated with long range hydrogen transfer. The mass spectra of the deuterium labeled samples provided evidence that direct hydrogen transfer takes place from positions as far as thirteen or more carbon atoms away from the oxygen function in preference to the McLafferty rearrangement. Examination of the spectra of the deuterium labeled derivatives shed further light on the mechanism of the loss of water from the molecular ion and various fragment ions.