title: Direct coupling of polymer-based microchip electrophoresis to online MALDI-MS using a rotating ball inlet.
abstract: We report on the coupling of a polymer-based microfluidic chip to a MALDI-TOF MS using a rotating ball interface. The microfluidic chips were fabricated by micromilling a mold insert into a brass plate, which was then used for replicating polymer microparts via hot embossing. Assembly of the chip was accomplished by thermally annealing a cover slip to the embossed substrate to enclose the channels. The linear separation channel was 50 microm wide, 100 microm deep, and possessed an 8 cm effective length separation channel with a double-T injector (V(inj) = 10 nL). The exit of the separation channel was machined to allow direct contact deposition of effluent onto a specially constructed rotating ball inlet to the mass spectrometer. Matrix addition was accomplished in-line on the surface of the ball. The coupling utilized the ball as the cathode transfer electrode to transport sample into the vacuum for desorption with a 355 nm Nd:YAG laser and analyzed on a TOF mass spectrometer. The ball was cleaned online after every rotation. The ability to couple poly(methylmethacrylate) microchip electrophoresis devices for the separation of peptides and peptide fragments produced from a protein digest with subsequent online MALDI MS detection was demonstrated.
authors.affiliation: Chemistry Department and Center for BioModular Multi-Scale Systems, Louisiana State University, Baton Rouge, LA 70803, USA.
authors.forename: Harrison K
authors.initials: HK
authors.lastname: Musyimi
authors.forename: Jason
authors.initials: J
authors.lastname: Guy
authors.forename: Damien A
authors.initials: DA
authors.lastname: Narcisse
authors.forename: Steven A
authors.initials: SA
authors.lastname: Soper
authors.forename: Kermit K
authors.initials: KK
authors.lastname: Murray
mesh_terms: D001839:Bombesin / Q000302:isolation & purification; D001920:Bradykinin / Q000302:isolation & purification; D045304:Cytochromes c / Q000737:chemistry; D046209:Electrophoresis, Microchip / Q000295:instrumentation / Q000379:methods*; D010446:Peptide Fragments / Q000302:isolation & purification; D019904:Polymethyl Methacrylate; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013373:Substance P / Q000302:isolation & purification; D014357:Trypsin / Q000378:metabolism
chemical_list: D010446:Peptide Fragments; D013373:Substance P; D045304:Cytochromes c; D019904:Polymethyl Methacrylate; D014357:Trypsin; D001839:Bombesin; D001920:Bradykinin