Studies on trimethylsilyl derivatives of 1-alk-1-enyl-2-acyl glycerols by gas-liquid chromatography mass spectrometry

Abstract

Trimethylsilyl derivatives of 1-hexadec-1-enyl-2-decanoyl and -2-octadecenoylglycerols and 1-octadec-1-enyl-2-decanoyl and -2-octadecenoylglycerols were subjected to analysis by a gas chromatograph mass spectrometer system. The characteristic ions are as follows: (1) ions at [M-15]+ and [M-90]+- are observed, 2 or 16 mass units less than those of the corresponding 1-alkyl-2-acyl or 1,2-diacyl derivatives; (2) the base peak is m/e 129; (3) the ion at [M-R1CH=CHO]+ or [R2COO+130]+ is present in high abundance; (4) ions at m/e 311 and 339, characteristic of trimethylsilyl derivatives of 1-hexadec-1-enyl and 1-octadec-1-enylglycerols, are due to [R1CH-CHO-1)+73]+, also confirmed from studies on the perdeuteriotrimethylsilyl derivatives; (5) several ions based on one acyl group, [R2CO]+, [R2CO+74]+ and [R2COO+74]+ are also observed.

A comparison of mass spectrometry methods for structural determination and analysis of phospholipids

“…The 1,3-diglycerides result from rearrangement reactions during the silylation process, and these reactions may be minimized by careful control of the conditions. These derivatives are amenable to GUMS analysis and are quite applicable for mixture analysis (67)(68)(69)(70)(71)(72)(73). For 1,2-diacyl glycerol derivatives, a low abundance M+' ion is observed along with characteristic ions of (M -15)'-and (M -90)+' (67).…”

Structural Determination of Lysophospholipid Regioisomers by Electrospray Ionization Tandem Mass Spectrometry†

“…The discrimination between individual regioisomers of lysophospholipids (e.g., 1-acyl-2-hydroxy- sn -glycero-3-phosphocholine vs 1-hydroxy-2-acyl- sn -glycero-3-phosphocholine) has represented a formidable obstacle in membrane chemistry. Due to its mechanistic implications (e.g., identification of the class of phospholipases activated during cellular stimulation and their phospholipid substrates) and synthetic importance, − the direct structural determination of lysophospholipid regioisomers from organic extracts of biologic tissues, where diminutive amounts of materials are available, has been a long-standing goal of phospholipid chemistry. − However, this goal has not been realized, in part due to the rapid intrapreparative isomerization of lysophospholipid regioisomers catalyzed by silica-based stationary phases leading to α-hydroxy acyl migration. ,− Furthermore, although NMR methods have successfully been utilized in the structural determination of lysophospholipid regioisomers, , the amounts of mass typically required for NMR analyses preclude its routine use in analyses of lysolipid isomers in biologic samples.…”

Acyl and phosphoryl migration in lysophospholipids: importance in phospholipid synthesis and phospholipase specificity

“…Another enzymatic technique, which has been employed to distinguish la and Ila, used the degradation of lysophospholipids to monoglycerides by phospholipase C (van den Bosch & van Deenen, 1965; Eibl & Lands, 1970). Although the resulting 1-and 2-monoglycerides can be analyzed by a variety of techniques (Hofmann, 1962;Wolfenden et al, 1964;Johnson & Holman, 1966;Satouchi & Saito, 1977;Sugatani et al, 1980;Matsuzawa & Hostetler, 1980), this is rather cumbersome and involves the problem of further acyl migration during the workup procedure. Spectroscopic methods such as IR (Slotboom et al, 1963(Slotboom et al, , 1967 de Haas & van , 13C NMR (Schmidt et al, 1977), or NMR (discussed below) can all detect spectral differences between the II) and phosphoryl (I ^III) migration of lysophospholipids derived from natural phospholipids (a series) and their enantiomorphs (b series).…”