Poly(glycidyl methacrylate-divinylbenzene) based immobilized pH gradient capillary isoelectric focusing coupling with MALDI mass spectrometry for enhanced neuropeptide analysis

Herein, we report an immobilized pH gradient (IPG) capillary isoelectric focusing-matrix-assisted laser desorption/ionization mass spectrometry (CIEF-MALDI MS) platform designed for the separation of complex neuropeptides. This platform features a poly(glycidyl methacrylate-divinylbenzene) (GMA-DVB)-based monolithic column for CIEF separation. Different from regular CIEF, carrier ampholytes are preimmobilized on the monolithic surface instead of being added to the sample. An off-line coupling of IPG-CIEF to MALDI MS has been established. Comparison with regular CIEF and optimizations are performed with bovine serum albumin tryptic peptides and extracted neuropeptide mixtures from crustacean Callinectes sapidus. It has been demonstrated that the separation of complex peptide mixtures in neutral and basic pH ranges can be achieved in less than 10 min with comparable separation efficiency with regular CIEF, while the MS signal is significantly enhanced when employing IPG-CIEF. Enhanced neuropeptide detection is also observed after coupling IPG-CIEF with MALDI MS.