Mass spectrum attribute

All analytical techniques are designed to provide the answer to one or both of the two important questions what is it and how much is there Mass spectrometry possesses attributes that allow it to contribute answers to both of these questions. The nominal (integral) m/z ratio of the molecular ion can sometimes be sufficient to identify a chemical compound, particularly if there is additional information available (either from the mass spectrum itself or another analytical technique). The presence of other signals in a mass spectrum attributable to... 

The peak at m/z 77 m the mass spectrum of chlorobenzene m Figure 13 41 is attributed to this fragmentation Because there is no peak of significant intensity two atomic mass units higher we know that the cation responsible for the peak at m/z 77 cannot contain chlorine... 

The submitters report that this product solidifies when cooled and melts at 21-22 and that the product is stable when stored in a refrigerator. The product exhibits infrared absorption (carbon tetrachloride) attributable to C=0 stretching at 1810 and 1765 cm. and a proton magnetic resonance singlet at B 1.50 (carbon tetrachloride). The mass spectrum of the product exhibits the following relatively abundant fragment peaks m/e (relative intensity), 60(10), 59(99), 57(34), 56(86), 55(47), 50(21), 44(100), 43(30), 41(91), 40(27), and 39(61). 

In the mass spectrum (Figure 8) of the corresponding ketal of 5-deoxy-D-xt/Zo-hexose, 5-deoxy-l,2-0-isopropylidene-D- rt/Zo-hexofuranose (11), the peak from C-4-C-5 cleavage, m/e 159, is of minor relative intensity. Since the ions at m/e 159 are the same from both isomers, 10 and 11, the intensity difference must be attributable to the lower stability of the primary radical formed from C-5 of 11 compared with the secondary radical from 10 ... 

The mass spectra of l-acyl-l//-l-benzazepines have been recorded.23 The mass spectrum of 3-mesyl-3/7-3-benzazepine shows an intense base peak at m/e = 142duetothebcnzazepinylium ion and a peak (51 %) at m/e — 115 (-HCN) which is attributed to the indenium cation.26 Fragmentation patterns for 1H- and 5/7-2-benzazepines40 and for 5//-dibenz[c,e]azepine5 are available. The electron-impact induced fragmentation pattern of 5//-dibenz[6,/]azepine displays an intense molecular ion as the base peak, and a moderately intense (M + 1) peak.5 ... 

Figure 2.22 Charge attribution (a) and deconvolution (b) of the electrospray positive ion mass spectrum of cytochrome c (see Figure 2.21)...

The general pattern of the mass spectrum and the presence of peaks at mlz 424, 426 and 442, attributed, respectively, to the molecular ions of lupeol, lupenone and betulin, suggest the presence of birch bark tar. This study provided the first evidence that birch bark tar was used for assembling bronze tools during the Iron Age in Europe. 

Figure 5.11 GALDI mass spectrum of copaiba balsam. The most intense peak (m/z 385) can be attributed to 3 acetoxy copaiferic acid...

The profile is characterized by substantial amounts of dicarboxylic acids, mainly formed in the oxidation of polyunsaturated Cl8 acids (linoleic acid, 08 2 and linolenic acid, 08 3), which are no longer detected after ageing. The presence of short chain dicarboxylic acid, and in particular of oxalic acid, is also characteristic of aged lipid layers. Moreover, in the 30 35 min interval, several peaks are detected and attributed to oxidized species of unsaturated 08 acids. Figure 7.7 reports the mass spectrum of the peak at 31.84, attributed to 13-OH-9-octadecenoic acid or 14-OH-9-octadecenoic acid. Its... 

Detailed examination of another madder preparation proved that the sample can be premordanted with alum. [ 19] After hydrolysis performed with hydrochloric acid and extraction with M-amyl alcohol, only four colourants are found alizarin, purpurin, and probably lucidin and ruberythric acid. Additionally, signals at m/z 525 and 539 are observed in the mass spectrum. Analysis of the preparation by inductively coupled plasma mass spectrometry (ICP MS) shows that aluminium and calcium are the main inorganic components of the sample. This is why it was suggested that the signal at m/z 539 can be attributed to the complex of aluminium with alizarin, and the second one, observed at m/z 525, to an aluminium-calcium cluster. 

Polyphenols, as one of the largest and most widespread class of plant compounds, are also present in saffron stigma. In the mass spectrum of the flavonoid fraction of the methanolic extract from saffron there were ions at m/z 611 and 633 which may be attributed to protonated and sodiated quasi-molecular ions of kaempferol diglycoside. [22] Flavonoids from the water extract can be isolated and concentrated... 

Vincovalinine (29), C44H56N4O7, has been isolated from C. ovalis as an amorphous material (62). The mass spectrum of 29 suggested the presence of a vindoline moiety showing the characteristic fragments at mfz 282, 135, 122, and 121, which was supported by the H-NMR spectrum. Comparison of the H-NMR spectrum of 29 with that of leurosine (11) indicated the absence of a methoxycarbonyl resonance, and a new signal was observed at 8 6.10 that could be attributed to 18 -H, establishing the 18 -demethoxycarbonylleurosine structure for 29. 

The reaction of diethylzinc with acetylacetone (acacH) in toluene resulted in the dimeric compound [EtZn(acac)]2 (39), which consists of a four-membered Zn202 ring . The El mass spectrum of 39 displayed three groups of peaks, attributed to the [Zn(acac)2] (miz 262), [EtZn(acac)] (m/z 192) and [Zn(acac)]+ (m/z 163) ions. The ion with m/z 192 simply represents a monomer fragment, whereas the ion with m/z 262 can be written as [M- EtiZn]. ... 

While D41 decomposes rather continuously in three equidistant steps, G2 shows two early steps of mass loss which are followed by a longer period of stagnation followed by a third step. With the help of the mass spectrum the single steps can be attributed to different events within the decomposition process. The first two steps are caused by the loss of water, obviously evaporated from two different sites of the solid, which explains the separated steps, both more than 150°C above the boiling point of water. The first loss of water may be due to the small amount of water which is enclosed in the inner spheres of the solid whereas at 400°C the leaving of crystal water is observed, which had obviously been in strong interaction with the inorganic compound. 

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