Preparative Separation of Mixtures by Mass Spectrometry

Abstract

A specially designed mass spectrometer which allows for preparative separation of mixtures is described. This mass spectrometer allows for large ion currents, on the order of nanoamperes, to be produced by electrospray and transmitted into a high vacuum. Accumulation of nanomole quantities of collected and recovered material in several hours is demonstrated. The use of high-velocity ions reduces space charge effects at high ion currents. Separation of mass occurs simultaneously for all ions, providing a 100% duty cycle. The use of a linear dispersion magnet avoids compression at higher m/z ratios. A deceleration lens slows the ions to allow for soft landing at low kinetic energy. The ions are neutralized by ion pairing on an oxidized metal surface. Retractable landing plates allow for easy removal of the separated components.

Ion soft-landing into liquids: Protein identification, separation, and purification with retention of biological activity

“…The landed material, along with the supporting substrate, was recovered in a buffered solution, incubated, diluted with methanol, and injecting into an LCQ Classic for ESI analysis. The ESI mass spectrum displays the sodiated N-acetylglucosamine hexamer (NAG) 6 as well as the sodiated N-acetylglucosamine pentamer (NAG) 5 , tetramer (NAG) 4 , trimer (NAG) 3 , and dimer (NAG) 2 resulting from lysozyme bioactivity. Soft-landed lysozyme (L) is also observed (see insert); (b) ESI-MS spectrum corresponding to hydrolysis of NAG 6 by solution-phase lysozyme (Blank 1); (c) ESI-MS spectrum corresponding to NAG 6 stored overnight at the same temperature, pH and in the same reaction medium as in case (a) and (b) except that no lysozyme was present.…”

“…Initial data is shown for a new approach to protein identification that combines top-down and bottom-up approaches by utilizing protein ion soft-landing from a protein mixture, followed by tryptic digestion of the landed material and detection of characteristic tryptic fragments by MALDI. , has been applied in experiments ranging from studies using chemically inert and structurally organized self-assembled monolayers (SAMs) as substrates for ion storage [2], to studies of ion mobility through ice and vapor deposited films [3,4], to experiments aimed at developing a separation method in a form of preparatory mass spectrometry [5,6]. Simple organic cations [7,8] [12][13][14] have all been the targets of examination by ion soft-landing.…”

“…M olecular ion soft-landing, characterized by deposition of intact molecules on surfaces at low kinetic energies [1], has been applied in experiments ranging from studies using chemically inert and structurally organized self-assembled monolayers (SAMs) as substrates for ion storage [2], to studies of ion mobility through ice and vapor deposited films [3,4], to experiments aimed at developing a separation method in a form of preparatory mass spectrometry [5,6]. Simple organic cations [7,8], metal clusters [9], polysaccharides [10], a nucleotide [11], and intact viruses [12][13][14] have all been the targets of examination by ion soft-landing.…”

IonCCD™ for Direct Position-Sensitive Charged-Particle Detection: from Electrons and keV Ions to Hyperthermal Biomolecular Ions

“…The spatial focusing on the focal plane is proportional to the width of the opening slit (S) located at the analyzer entrance and to the ratio R m /R e (magnetic and electric radius described by the ion). Several types of detectors have been used with the MH-MS, such as: photographic plate [6], ion collectors coupled to electrometers [7], electro-optical imaging detector (EOID) [8,9], Spiraltron matrix coupled to a resistive anode [10], collector cups for linear mixture separation and material deposition (soft-landing) using a nonhomogeneous magnetic field [11,12], delta-doped CCD, [13] faraday-strip array detector [14][15][16][17][18][19][20][21][22][23], CMOS based pixilated array detector [24], and of course the modified CCD array detector (IonCCD) in early work [1]. Using an ESI source, we present results for the IonCCD coupled with a miniature MH-MS showing simultaneous biological mixture separation for potential micro-array ion deposition applications [25].…”

<em>In Situ</em> SIMS and IR Spectroscopy of Well-defined Surfaces Prepared by Soft Landing of Mass-selected Ions

“…Ions have been produced through processes such as electrospray ionization (ESI) 10,58,59 , matrix-assisted laser desorption/ionization (MALDI) 21 , electron impact ionization (EI) 60,61 , pulsed arc discharge 62 , inert gas condensation 36,63 , magnetron sputtering 64,65 , and laser vaporization 25,66,67 . Mass selection of gas-phase ions prior to soft landing has been achieved principally employing quadrupole mass filters 58,68,69 , magnetic deflection devices 70 , and linear ion trap instruments 8,59 . A particularly notable advance in ion soft landing methodology occurred recently with the successful implementation of ambient ion soft-and reactive landing by Cooks and co-workers 71,72 .…”