Fragmentation Patterns Of Compounds Research Articles

Mass spectrometry based fragmentation patterns of nitrosamine compounds.

Nitrosamines are a class of mutagenic substances that can display high carcinogenic potential. New chemical entities may have the potential to form unique nitrosamines specific to the drug substance. It is therefore essential to understand the gas-phase fragmentation behavior of nitrosamine compounds to enable the development of analytical methods to characterize novel nitrosamine compounds. The gas-phase fragmentation behavior of eight model nitrosamine compounds representing the common substructures seen in many small molecule pharmaceutical compounds was studied with positive electrospray ionization tandem mass spectrometry (ESI-MS/MS). The fragmentation patterns of these compounds under various collision parameters available in commercially available mass spectrometers were studied. Protonated nitrosamine compounds produced diagnostic fragment ions upon MS/MS. Three primary structure-dependent fragmentation pathways were observed. The first pathway involves the loss of 30 Da which corresponds to the loss of the NO radical from the protonated nitrosamine compound (Group 1). The second and third fragmentation pathways, which have not been reported for nitrosamine compounds, proceed via the loss of H2 O from the protonated nitrosamine compound (Group 2), and elimination and a loss of 46 Da (loss of NH2 NO) from the nitrosamine compound (Group 3). Results presented in this work provide an overview of the gas-phase fragmentation patterns of nitrosamine compounds and may be useful in identifying novel nitrosamine compounds in complex matrices.

Fragmentation Study of Daphniphyllum Alkaloids by Electrospray Ionization Quadrupole Time-of-flight Mass Spectrometry

A series of 16 Daphniphyllum alkaloids isolated from Daphniphyllum macropodum were investigated by electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-QTOF-MS/MS) in positive-ion mode. Deuterium labeling experiments were carried out to identify the major product ions. Although compounds have similar structures, the profiles of their MS/MS spectra vary greatly. For compounds 1 and 2, abundant product ions both in high and low mass range can be detected. A six-member H rearrangement and the cleavage of C1-C2 bond connecting rings A, C and D play an important role in providing the product ions in low mass range. For compounds 3-9, the relative abundance of product ions in low mass range is low. This may result from the loss of HCOOCH3 occurring readily because C4-C5 double bond prevents six-member H rearrangement. Main fragmentation patterns of compounds 10-14 are the loss of the different side-chain groups and the cleavage of pyrrol and pyridine rings. A series of ion clusters detected in low mass range are characteristic ions for compounds 10-14. Fragmentation patterns of compounds 15 and 16 were elucidated. Four groups of isomers in these compounds were distinguished by characteristic product ions or fragmentation patterns.

Post-target Analysis for the Volatile Compounds from SaltyAlpinia oxyphyllae Fructuswith Headspace-gas Chromatography-quadrupole/time of Flight Mass Spectrometry

Post-target analysis is a superior method for qualitative analysis. This method can make a rapid, accurate and wide-scope screening for non-target and target compounds, and it has been used widely in the metabonomics, environmental analysis and pesticide residues. With post-target method to analysis non-target compounds, retention index, accurate mass and library were applied to investigate non-target analytes and then a total of 119 compounds were identified. Within those 119 compounds, there are different kinds of compounds, such as aliphatic aldehyde, aromatic ketone, aromatic aldehyde, monoterpene and its oxide, sesquiterpenes and its oxide and so on. Eremophilene is the best peak ingredient, p-cymene, aromadendrene, nootkatone and delta-cadinene are the main ingredients. Besides, nootkatone is the main active ingredient according to previous pharmacology research. Narrow mass window extracted ion chromatograms (nw-XIC) can decrease background noise greatly and improve the signal-to-noise rate. Hence, the trace level or co-elution compounds can be identified. With the post-target analytical method for target analytes, we calculated retention time from retention index of target compounds, and then nw-XIC (mass window 0.02 Da) was carried out. Four characteristic ions of target compounds were extracted to get extracted ion chromatograms at calculated retention time. As peaks at calculated retention time had the same chromatographic behavior, we identified three target compounds: nootkatol, alpha-cyperone and perillaldehyde. Tandem mass technology has been widely used since its introduction in the 1970s, it was used in trace analysis, chemical reaction mechanistic studies and propose the fragmentation pattern of compounds. In this paper, we got first-stage mass spectra and second-stage mass spectra data in one experiment. Moreover, we could obtain accurate mass of precursor ion and product ion from second-stage mass spectra at the same time, then we inferred the MS fragmentation pattern of compounds. This method is more simple, convenient and accurate than the traditional tandem mass spectrometry. Myrtenal was identified in this post-target way. Post-target analytical method can distinguish compounds from complex matrix samples as many as possible. This method solves the problems of co-elution and high background and can be used to investigate the medicine's pharmacology and toxicology mechanism.

Electrospray mass spectrometry of trimethyllead and triethyllead with in-tube solid phase microextraction sample introduction

A study of positive ionization electrospray mass spectrometry (ES-MS) was performed on trimethyllead (TML) and triethyllead (TEL). The system consisted of in-tube solid phase microextraction (SPME) coupled directly to an electrospray mass spectrometer. Fragmentation patterns of compounds were observed by applying different fragmentation voltages. High voltages produced sufficient fragmentation to elucidate the dissociation of the trialkyllead compounds. Electrospray mass spectrometry has been shown to be a suitable detection system for organolead speciation. Applying fragmentation energy programming, it might be possible to obtain in parallel the molecular and atomic signals of lead compounds. Copyright 1999 John Wiley & Sons, Ltd.

Spectroscopic Studies of 1‐Aryl‐2,2‐Dichlorocyclopropanes

AbstractSeventeen 1‐aryl‐2,2‐dichlorocyclopropanes were examined by using IR, 13C NMR, and mass spectrometry. The data obtained from IR and 13C NMR spectra indicate that the bond strength of carbon‐chlorine on the cyclopropane ring and the electron density of that carbon depend on the substituent. The mass fragmentation patterns of compounds in this series resemble those of the dibromo analogues. The fragmentation mechanism is proposed to involve the formation of indenium ion through an electrocyclization.

Beitrag zur Massenspektrometrie substituierter α, ω‐Alkandiamine. 29. Mitteilung über massenspektrometrische Untersuchungen

Contribution to the mass spectrometry of substituted α,ω‐alkane diaminesThe main mass spectral fragmentation pattern of compounds of types 1 to 4 is discussed. After loss of C6H5 · CH2 · from the molecular ion the acid correspondin to the N,N‐disubstituted residue is splitted off. The mechanism of this fragmentation reaction depends on the member of CH2‐groups between the two nitrogen atoms (Schemes 1 and 3) and on the substitution pattern of both nitrogens (Scheme 2).

A mass spectral study of some symmetric and unsymmetric sulfides, disulfanes, and trisulfanes

The low-resolution mass spectra of 13 trifluoromethyl and/or methyl sulfur-containing compounds (CF 3S n CF 3, CF 3S n CH 3, CH 3S n CH 3, CF 3S m Cl, and CH 3S m Cl; n = 1, 2, 3; m = 1, 2) are reported and discussed. There is a considerable similarity between the fragmentation pattern of compounds with the same terminal groups. However, with a fluorinated and a non-fluorinated methyl group, the major fragmentation products produced are similar to those for the dimethyl compounds.