Preliminary investigation of electrodynamic charged droplet processing to couple capillary liquid chromatography with matrix-assisted laser desorption/ionization mass spectrometry.
Charged droplet processing methodology, that utilizes electrodynamic levitation technology to control the trajectories of picoliter volume charged droplets and deliver them to a target plate at atmospheric pressure, has been developed. Termed wall-less sample preparation (WaSP), this methodology offers several features that could prove beneficial to the preparation of sample spots from separation column effluents for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis. These features include solute pre-concentration factors of 10(1) to 10(3) due to volatile solvent evaporation prior to droplet deposition onto the target plate, high spatial accuracy of the deposition position of each processed droplet (+/-5 microm), and the ability to prepare sample spots as small as 20 microm in diameter from a single droplet. Here a new mode of operation of this methodology is described and used as an offline post-column pre-concentrating interface between capillary liquid chromatography (capLC) and a target plate for offline MALDI-MS. Using a fraction from the capLC separation of peptides produced by the proteolytic digestion of the protein cytidine 5'-triphosphate:phosphocholine cytidylyltransferase, MALDI sample spots were prepared using the dried-droplet method, direct piezoelectric droplet dispensing, and the processing of piezo-dispensed droplets by WaSP. The sample spot morphology was investigated using light microscopy, and peptide ion abundances produced by MALDI were measured using time-of-flight (TOF) MS. The advantages of developing an online capLC/WaSP interface with MALDI-MS in the future are discussed along with some of the challenges that may be encountered in such an endeavor.
Bogan
Michael J
MJ
Department of Chemistry, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada.
Agnes
George R
GR
D019916:Choline-Phosphate Cytidylyltransferase / Q000737:chemistry; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000295:instrumentation* / Q000379:methods; D003570:Cytidine Triphosphate / Q000737:chemistry; D008832:Microchemistry / Q000295:instrumentation / Q000379:methods; D010455:Peptides / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000295:instrumentation* / Q000379:methods
D010455:Peptides; D003570:Cytidine Triphosphate; D019916:Choline-Phosphate Cytidylyltransferase