Positive ion MALDI-TOF

Fig. 10.6. Linear mode positive-ion MALDI-TOF spectra of ribonuclease B in 80 mM urea, (a) 300 fmol in CHCA, (b) 600 fmol in DHB, and (c) 300 fmol in CHCA/DHB matrix mix. Reproduced from Ref. [71] by permission. Elsevier Science, 2003.

The LC/MS does not allow separation and identification of oligomers higher than pentamers because the number of diastereoisomers is large and their separation is not possible. By having positive-ion MALDI-TOF in the reflectron mode, determination of (+)-catechin, (-)-epicatechin oligomers, and their galloylated derivatives up to a heptamer in grape seed extracts as sodium adducts [M+Na]+ is possible... 

Figure 6.31. Positive-ion MALDI-TOF reflectron mode mass spectrum of grape seed extract (matrix 2,5-dihydroxybenzoic acid). (Reprinted from Journal of Agricultural and Food Chemistry, 48, Yang and Chien, Characterization of grape procyanidins using high-performance liquid chromatography/mass spectrometry and matrix-assisted laser desorption time-of-flight mass spectrometry, p. 3993, Copyright 2000, with permission from American Chemical Society.)...

Although fatty acyl residues are present in all lipids, the analysis of free fatty acids by MALDI-TOF MS is rather difficult as they show-due to their relatively low molecular weights-a significant overlap with the matrix. This particularly holds if fatty acids at low concentrations have to be analyzed. One possibility to overcome this problem is the use of mesotetrakis(pentafiuorophe-nyl)porphyrin (Ayorinde et al. 1999) as matrix It could be shown that the analysis of free fatty acids obtained by alkaline saponification of different plant oils is possible by this matrix (Ayorinde et al. 2000). As an excess of sodium acetate was added, exclusively the Na adducts of the sodium salts of the fatty acids were detected by positive ion MALDI-TOF MS. Therefore, problems with peak assignments did not occur. Unfortunately, this approach... 

Fig. 21.1 Positive ion MALDI-TOF mass spectra of triolein (a), l-palmitoyl-2-oleoyl-sn-phosphatidylcholine (b), l-palmitoyl-2-oleoyl-sn-phosphatidylethanolamine (c) and 1-pahni-toyl-2-oleoyl-sn-phosphatidylserine (d). In all cases a 0.5 M solution of DHB in methanol was used as matrix and the sample solutions (0.2 mg/ml) diluted 1 1 (v/v) with the matrix. All peaks are marked according to their m/z ratio and the DHB matrix peaks are marked with asterisks...

Fig. 21.3 Typical positive ion MALDI-TOF mass spectra of a chloroform-methanol extract of LDL (a) and HDL (b). The insert emphasizes the most relevant mass range of the FIDL sample. The peak labeled with an asterisk is caused by the matrix. Reprinted with modification from Journal of Lipid Research 42 (2001) 1501-1508...

Fig. 21.4 Positive ion MALDI-TOF mass spectra of an organic extract of human blood plasma recorded with DFiB as matrix. Trace (a) represents the original extract, whereas all other samples were diluted with CHCI3 prior to mixing with matrix. The following dilutions were used 1 5 (b), 1 10 (c), 1 25 (d)and 1 50 (e). The peaks at m/z = 577.5 and 603.5 are caused by the loss of one acyl residue from the TAG. Please note the arising of triacylglycerol peaks and the reduction of PC at higher dilutions...

Fig. 21.6 Typical positive ion MALDI-TOF mass spectra of organic extracts of spermatozoa from a healthy volunteer. Before MS analysis, spermatozoa were separated into annexin V-negative (a) and annexin V-positive (b) spermatozoa. Peaks are labeled according to the corresponding m/z ratios. The most indicative peak groups are marked with grey bars. The asterisk indicates a typical DHB matrix peak (m/z = 551). Abbreviations LPC, lyso-phos-phatidylcholine PC, phosphatidylcholine. Reprinted from Glander et al.. Deterioration of spermatozoal plasma membrane is associated with an increase of sperm lyso-phosphatidyl-cholines, Andrologia, 2002 with permission from Blackwell...

Positive-ion MALDI-TOF spectra of a polyethylene glycol SEC-standard sample obtained in (a) linear mode (b) reflection mode and (c) delayed extraction mode. (Reprinted with permission from Ref. 20, Copyright 1999 John Whey Sons Ltd)... 

Positive-ions MALDI-TOF mass spectra of Ny6 samples (a) reacted with diaminohexamethyl-ene (b) reacted with decylamine (c) reacted with adipic acid (d) hydrolyzed with water in methansulfonic acid. (Continued)... 

Positive ion MALDI-TOF spectra for sample PEG 4100 in the linear mode (a), for sample PEG 4100 in the reflection mode (b), and for sample PEG 2000 in the reflection mode (c). (Reprinted with permission from Ref. 141, Copyright 1995 American Chemical Society)... 

The positive ions MALDI-TOF spectrum of poly(butylene adipate diol)s, made by bulk polymerization of terephthaloyl chloride with a molar excess of 1,4 butanediol, shows only one series of peaks, extending over mass range 1000-6000 Da. These may be assigned to dihydroxyl-terminated oligomers. ° ... 

Positive ion MALDI-TOF mass spectrometry of macromolecules prepared by ring-opening polymerization of e-caprolactone with tin(II) octoate [Sn(Oct)2], in the presence of R OH (water or alcohol) as co-initiator, revealed that there is a sizeable population of macromolecules having Sn atoms in the chains, either linear and/or cyclic ones ... 

Positive ions MALDI-TOF mass spectmm of the low molar mass methanol soluble oligomers of a high conversion (98%) poly(D,L)lactide sample, recorded in reflection mode using HABA as a matrix. (Reprinted with permission from Ref. 142, Copyright 1996 American Chemical Society)... 

Positive ions MALDI-TOF MS spectra of unfractionated PCI (a) and PC2 samples (b). 

Positive-ion MALDI-TOF mass spectra of a copolymer containing units of hydroxybutirate and units of hydroxyvalerate. (a) Experimental mass spectrum and (b) calculated mass spectrum. 

Positive-ion MALDI-TOF mass spectrum of a copolymer containing butylene adipate (A) and butylene sebacate (B) units. 

Figure 7.3 Positive-ion MALDI-TOF mass spectra of selected triacylglycerols. (a) TAG 3x18 0 (b) TAG 3x18 1 (c) TAG 3x18 2 (d) TAG 3x18 3. All spectra were recorded using 0.1 ig of TAG and 0.5 M...

The positive-ion MALDI-TOF mass spectra of four selected TAGs are shown in Figure 7.3. These TAGs were chosen because they differ in their content of double bonds each TAG is detectable as the Na adduct, and the cleavage of one sodiated fatty acid is readily detectable. For instance, the mass difference of 306 amu in trace (a) corresponds to the loss of sodium stearate. 

Figure 7.6 Positive-ion MALDI-TOF mass spectra of an organic extract from hen egg yolk, (a) Trace recorded in the presence of DHB (b) Trace recorded in the presence of 9-aminoacridine (9-AA). Peaks are labeled...

The positive-ion MALDI-TOF mass spectra of brain are dominated by PC, LPC and SM, whereas PI is the most abundant negatively charged PL. In order to be able to detect further lipid species, however, a previous separation of the total brain extract into the individual lipid classes is necessary [88]. Because of the rapid performance and simple equipment involved, TLC can be used advantageously when only small amounts of lipids are necessary for subsequent analysis by MS [132]. Indeed, by using a careful sample preparation and suitable TLC conditions, even minor glycolipids can be detected and investigated [133]. 

Figure 7.10 Expanded region of a TLC-sepa-rated egg yolk extract and the corresponding positive-ion MALDI-TOF mass spectra recorded directly from the indicated positions on the plate. Only the relevant mass regions of each PL class are shown, and assignments are provided directly in the individual traces. Data given in parentheses correspond to theoretical masses, and were introduced to...

Recently, Griesinger et al. [6] examined TLC-MS of lipids with positive ion MALDI-TOF on various thickness silica gel layers 200, 100, and 60 pm. As the layer thickness decreases, there was less matrix background and increased sensitivities for the compound studied, with the best results on the 60-pm layer. This was true whether the sorbent bed was made up of TLC or HPTLC size particles. 

The TLC lane of the egg yolk extract and some selected positive ion MALDI TOF mass spectra are shown in Figure 13.3 to illustrate the achievable spectral... 

FIGURE 13.5 Positive ion MALDI-TOF mass spectra of hen egg yolk PE recorded directly from TLC plates with different thicknesses of the stationary phase. The thickness of the used HPTLC plates is indicated in the figure. Spectra labeled with Control correspond to the PE mixture desorbed directly from a conventional stainless steel MALDI target. Only selected mass spectra are shown. Note that reasonable peak intensities can be exclusively achieved in the case of a reduced silica gel thickness, but not if 200- xm plates are used. (From Griesinger, H. et al., Anal. Biochem., 451,45-47, 2014. With permission.)... 

Figure 3.25 Positive ion MALDi/TOF mass spectrum of poiy(butyi methacryiate). The data were acquired in the iinear mode and 11-point smoothed.

Fig. 1. Positive ion MALDI TOF mass spectra of intact Bacillus spore species. The peaks denoted by arrows in the mass/charge range 7000 correspond to biomarker proteins (SASP) that differ in amino acid sequence between the two species and allow species differentiation and identification.

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