Profiling of complex lipids in marine microalgae by UHPLC/tandem mass spectrometry

Unambiguous regiochemical assignment of sulfoquinovosyl mono‐ and diacylglycerols in parsley and spinach leaves by liquid chromatography/electrospray ionization sequential mass spectrometry assisted by regioselective enzymatic hydrolysis

“…By the same approach the synthesis of an SQDG bearing deuterated palmitic (D 31 –16:0) and stearic (D 35 –18:0) acids at the sn 1 and sn 2 positions of glycerol, respectively, has been also reported . Tandem mass spectrometric (MS/MS) analysis, performed on the corresponding deprotonated SQDG molecule ([M − H] − ) under higher‐energy collisional dissociation (HCD) conditions, confirmed that the acyl chain loss as fatty acid from the sn 1 position was prevailing over that from the sn 2 position . The use of deuterated analogues allowed some mechanistic information to be obtained; indeed, a charge‐remote fragmentation involving the α‐methylene C–D bond breaking of the neighbouring acyl substituent was suggested thus providing a confirmation of the fragmentation mechanism previously proposed by Zianni et al Therefore, a strong support for the above‐mentioned MS‐based regiochemical assignment rule for SQDG has been achieved.…”

“…Mass spectrometry (MS) has played a key role in the identification of SQDG in recent years and several different approaches have been proposed, including matrix‐assisted laser desorption/ionization with quadrupole ion‐trap low‐energy collision‐induced dissociation and time‐of‐flight MS (MALDI‐QIT‐TOF‐CID‐MS n ), fast atom bombardment (FAB)‐CID‐MS/MS, electrospray ionization (ESI)‐triple quadrupole CID‐MS/MS, ESI‐linear ion trap CID‐MS/MS, and ESI‐Orbitrap MS . MS‐based regiochemical assignment is particularly challenging in the case of sulfolipids because (i) the collision energy value during CID‐MS/MS investigation can significantly affect fragmentation pathways and (ii) no commercial standards with known regiochemistry are available.…”

“…MS‐based regiochemical assignment is particularly challenging in the case of sulfolipids because (i) the collision energy value during CID‐MS/MS investigation can significantly affect fragmentation pathways and (ii) no commercial standards with known regiochemistry are available. Therefore, the adoption of different interpretation rules of the fragmentation spectra has led to different and conflicting structural identifications, thus requiring support from data obtained by techniques other than MS.…”

“…More recently, a chemo‐enzymatic preparation of SQDG has been proposed to obtain a wide diversity of regio‐ and stereoisomers of these compounds. By the same approach the synthesis of an SQDG bearing deuterated palmitic (D 31 –16:0) and stearic (D 35 –18:0) acids at the sn 1 and sn 2 positions of glycerol, respectively, has been also reported .…”

“…More recently, a chemo‐enzymatic preparation of SQDG has been proposed to obtain a wide diversity of regio‐ and stereoisomers of these compounds. By the same approach the synthesis of an SQDG bearing deuterated palmitic (D 31 –16:0) and stearic (D 35 –18:0) acids at the sn 1 and sn 2 positions of glycerol, respectively, has been also reported . Tandem mass spectrometric (MS/MS) analysis, performed on the corresponding deprotonated SQDG molecule ([M − H] − ) under higher‐energy collisional dissociation (HCD) conditions, confirmed that the acyl chain loss as fatty acid from the sn 1 position was prevailing over that from the sn 2 position .…”