title: Portable, Battery Operated Capillary Electrophoresis with Optical Isomer Resolution Integrated with Ionization Source for Mass Spectrometry.
abstract: We introduce a battery operated capillary electrophoresis electrospray ionization (CE/ESI) source for mass spectrometry with optical isomer separation capability. The source fits in front of low or high resolution mass spectrometers similar to a nanospray source with about the same weight and size. The source has two high voltage power supplies (±25 kV HVPS) capable of operating in forward or reverse polarity modes and powered by a 12 V rechargeable lithium ion battery with operation time of ~10 h. In ultrafast CE mode, in which short narrow capillaries (≤15 μm i.d., 15-25 cm long) and field gradients ≥1000 V/cm are used, peak widths at the base are <1 s wide. Under these conditions, the source provides high resolution separation, including optical isomer resolution in ~1 min. Using a low resolution mass spectrometer (LTQ Velos) with a scan time of 0.07 s/scan, baseline separation of amino acids and their optical isomers were achieved in ~1 min. Moreover, bovine serum albumin (BSA) was analyzed in ~1 min with 56% coverage using the data-dependent MS/MS. Using a high resolution mass spectrometer (Thermo Orbitrap Elite) with 15,000 resolution, the fastest scan time achieved was 0.15 s, which was adequate for CE-MS analysis when optical isomer separation is not required or when the optical isomers were well separated. Figures of merit including a detection limit of 2 fmol and linear dynamic range of two orders of magnitude were achieved for amino acids.
authors.affiliation: Department of Forensic Sciences, George Washington University, Washington, DC, 20007, USA. moinim@gwu.edu.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Moini
authors.affiliation: Department of Forensic Sciences, George Washington University, Washington, DC, 20007, USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Rollman
mesh_terms: D000596:Amino Acids / Q000032:analysis*; D000818:Animals; D002417:Cattle; D004867:Equipment Design; D007536:Isomerism; D057230:Limit of Detection; D013058:Mass Spectrometry / Q000295:instrumentation*; D012710:Serum Albumin, Bovine / Q000032:analysis*; D053719:Tandem Mass Spectrometry / Q000295:instrumentation*
chemical_list: D000596:Amino Acids; D012710:Serum Albumin, Bovine
keywords: Amino acids; Battery operated CE; Integrated ionization source; Optical isomers; Ultrafast CE