Daughter spectrum

The operative mechanisms have been deduced by considering various peaks identified in the daughter spectrum employing the reflectron technique. One corresponds to a mass loss of 32 amu from a parent ion cluster that enters the drift region as H+(CH3OH) via ... 

MS/MS data are very explicit daughter spectra may reveal structural characteristics of isolated portions of the molecule (4), and under certain conditions, all masses in a daughter spectrum are single-event neutral losses from the parent ion. Thus, clear... 

The procedure for obtaining the spectrum/substructure relationships is as follows. For a selected known compound, a daughter spectrum is acquired for every mass value greater than 1 relative intensity that appears in the primary spectrum of that compound. These... 

After the spectral matching process has been completed, the list of compounds with the top matching daughter spectra are identified and retrieved for each daughter spectrum in the reference compound. The molecular structures of the compounds with best matching spectra are drawn and compared for common substructures. The common substructures yield candidate spectrum/substructure correlations. Additional compounds are then tested to confirm or modify each correlation. Once the daughter spectrum is correlated with one or more substructures, this daughter spectrum is stored in the spectrum data base and is linked to the associated substructures stored in the structure data base. 

The results of the match of the m/z 149 daughter spectrum of di-n-octylphthalate against m/z 149 daughter spectra from other compounds in the reference library is given in Table III. The... 

From the daughter spectra of di-n-octylphthalate, we were able to determine two spectrum/substructure correlations the 149+ daughter spectrum to structure I in Figure 3 and the 105+ daughter spectrum to structure III in Figure 3. In order to obtain spectrum substructure relationships for the alkyl portions of the reference molecule di-n-octylphthalate, we would then match other portions of the complete MS/MS spectrum against those of compounds containing alkyl substructures. However, this portion of the reference library has not yet been developed. Thus, to complete the structure elucidation we have used standard methods of spectral interpretation (11). As will be shown, these methods can also lead to useful spectrum/substructure relationships. 

Since the substructure represented by the daughter spectrum of the m/z 149 ion was the largest identifiable substructure in the compound, the parent spectrum of m/z 149 was used to obtain data related to the R groups attached to the phthalate substructure (Figure 6). The largest ion (149+) associated with the phthalate... 

Figure 7, Daughter spectrum of the C-containing protonated molecular ion of di-n-octylphthalate.

For example, to determine the empirical formula of di-n-octylphthalate, the daughter spectrum of the containing molecular ion (392) was obtained (Figure 7). The relative peak areas of adjacent peak pairs at m/z 149 and 150 is 2 1. This indicates that the M+1 ion is twice as likely to lose a atom as retain it. Thus the ratio of the number of carbon atoms lost to those retained is 2 1. Since the identified phthalate substructure contains 8 carbons, the unknown compound (di-n-octylphthalate) must contain 24 carbon atoms. These data, along with the molecular weight of 390 as determined from the conventional Cl mass spectrum of the unknown was fed into the empirical formula generator and the output was one empirical formula C24H38O4. 

In the same study, an unexpected result was observed in the daughter spectrum of the intact cation (m/z 162) from carnitine (see Matrix effects, above). The base peak in SIMS MS/MS is m/z 103, corresponding to loss of trimethylamine by rearrangement, while the same ion in the SIMS survey spectrum is nearly absent. This is a striking case of different behavior between SIMS and gas... 

Compound Molecular Mass MH+ Daughter Spectrum Comments Peak Intensity Bile Urine ... 

What is the identity of the peak at m/z=213, appearing in the TSP/MS spectrum of aminonitrazepam, and of the peak at m/z=121, appearing in the daughter spectrum of aminonitrazepam and used in SRM in analyzing the post mortem sample. 

Figure 1. Daughter spectrum of aminonitrazepam. Direct injection in thermospray MS, solvent 20% methanol in 50 mmol/1 ammonium acetate, repeller 50V, vaporizer 120°C, collision gas air at 0.05 Pa, collision energy 60 eV.

Simultaneous variation of magnetic and electric fields (linked scan methods, conventional or reversed geometry) B/E, constant parent spectrum E /V, simulated MIKE B /E, constant daughter spectrum (B/E) (1 — constant neutral fragment ... 

Figure 3. n mass spectrum (a) and daughter spectrum of m/z 126 (b) for Pinaoolyi methyiphosphonofluoridate. 

Figure 8. Capillary GC/MS/MS chromatogram for daughter Ions of m/z 158 (M for 2 ng of mustard /6/). Daughter spectrum obtained for mustard Inset of Figure.

Fig. 10 illustrates a typical reaction ion monitoring chromatograms for 100 pg of the studying compounds. Signal-to-noice ratio was excellent and in the majority of dau ters more than 400 1. An interpretable daughter spectrum was obtained also for 100 pg of DEMP and dibenzo/b,f/-l,4-oxazepin (S/N>10). 

For MRM mode analysis of niacin by IDMS one should be aware of an isotopic effect in the fragmentation of nicotinic add. The natural nicotinic acid daughter spectrum (Figure 19.1b) suggests that the transitions 124 - 80 or 124 78 would be suitable for MRM analysis. The fragment at m/z 80 cor-... 

The feasibility of on-line electrochemistry mass spectrometry in the study of electrode processes has recently been demonstrated by Heitbaum et al. . We have tested the potential of on-line mass spectrometry in the study of redox reactivity of biological compounds with uric acid as a probe. Electrochemical oxidation of uric acid has been studied extensively . The scheme in Figure 6 shows the electrochemical oxidation pathway of uric acid and indicates intermediates and products which were identified by on-line electrochemistry thermospray mass spectrometry (EC/TSP/MS/MS) . In our studies, tandem mass spectrometry (MS/MS) was used to obtain structurally informative fragmentation patterns (daughter spectra) of standards for comparison to the mass spectra of intermediates and products obtained by EC/TSP/MS/MS. This, for example, allowed identification of allantoin through its characteristic daughter spectrum. It also allowed confirmation of the structural features of the intermediate, bicyclic carboxylic acid, which apparently forms from the imine alcohol in the oxidation of uric acid. The intermediates and products which were identified in this way are indicated in the scheme, and mass spectral results are summarized in Table 1. 

MS/MS Daughter Spectrum (jtRA) MS(jtRA) MS/MS Daughter Spectrum ( RA)... 

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