90.two, respectively. The calculated MBR value (290 + 190 – 347 = 133) recommended FAME with 3 conjugated
90.2, respectively. The calculated MBR worth (290 + 190 – 347 = 133) suggested FAME with 3 conjugated double bonds (Table 1). Diagnostic ions have been accompanied by less abundant satellite peaks differing from and ions by 14 or 15 Da. These fragments representing cleavages at a lot more distant C bonds had been important for distinguishing double and triple bonds. The elemental composition with the major fragments within the spectra of FAME standards was confirmed by Orbitrap high-resolution information (Supplementary Components Table S1). two.1. Mass Spectra of Requirements with Conjugated Double Bonds The system with two conjugated double bonds was investigated utilizing standards of FAME 18:2n-7t,9t (Mangold’s acid methyl ester) and FAME 18:2n-7c,9c (ricinenic acid methyl ester). The fragments within the MS/MS spectrum for FAME 18:2n-7t,9t (Figure 1) have been rationalized as follows: n-7 peak at m/z 264.1, n-9 peak at m/z 238.two, n-7 peak at m/z 166.1, and n-9 peak at m/z 192.1. The MBR worth calculated in the two most intense fragments within the spectrum (i.e., m/z 192.1 and m/z 264.1) was 107. Regardless of the presence of satellite fragments differing by 14 Da in the diagnostics peaks, the spectrum provided clear evidence of two conjugated double bonds within the n-7 and n-9 positions. The spectrum of FAME 18:2n-7c,9c possessing the opposite geometry on each double bonds looked related (Figure S1), which confirmed the negligible impact of double bond geometry on the adduct fragmentation documented earlier [19]. The MS/MS spectrum of punicic acid methyl ester with three conjugated double bonds (FAME 18:3n-5c,7t,9c) is shown in Figure 2. The major fragments inside the spectrum have been formed by cleavages before and immediately after the series of double bonds. They have been easily distinguishable in the other ions. One of the most abundant fragments n-5 at m/z 290.two and n-9 at m/z 190.2 delimited the group of conjugated double bonds and Compound 48/80 MedChemExpress corresponded to an MBR value of 133. The fragments formed by the cleavages GLPG-3221 manufacturer involving conjugated double bonds n-7 (m/z 264.3), n-9 (m/z 238.2), n-7 (m/z 164.two), and n-5 (m/z 138.2) have been of low intensities but discernable in the spectrum. Precisely the same diagnostic fragments and MBR value could theoretically be anticipated for any FAME with two cumulated double bonds separated by a single methylene group from the third double bond. Such an arrangement of double bonds will be, nevertheless, clearly distinguishable since the system of cumulatedMolecules 2021, 26,5 ofMolecules 2021, 26,Figure 1. APCI MS/MS CID spectrum of [M + 55]+adduct of Mangold’s acid methyl es double bonds manifests + 192 – abundant 5 of (m/z 18:2n-7t,9t); MBR = 264 itself by 349 = 107. + 1 Da ion (Section 2.three.three). Such an ion251 or m/z 291 in this case) is not present in the spectrum. Thus, the spectrum in Figure two may be unambiguously interpreted as FAME 18:3n-5,7,9.Figure 1. APCI MS/MS CID spectrum of [M + 55]+ adduct of Mangold’s acid methyl ester +Figure 1. APCI MS/MSMBR = 264 + 192 – 349 = 107. (FAME 18:2n-7t,9t); CID spectrum of [M + 55] adduct of Mangold’s acid methyl ester (FAME 18:2n-7t,9t); MBR = 264 + 192 – 349 = 107.The MS/MS spectrum of punicic acid methyl ester with three conjugate bonds (FAME 18:3n-5c,7t,9c) is shown in Figure two. The major fragments within the had been formed by cleavages prior to and just after the series of double bonds. They w distinguishable in the other ions. By far the most abundant fragments n-5 at m/z n-9 at m/z 190.two delimited the group of conjugated double bonds and corresp an MBR worth of 133.
