A novel gas chromatograph-mass spectrometer (GC-MS) based on a miniature toroidal ion trap mass analyzer (TMS) and a low thermal mass GC is described. The TMS system has an effective mass/charge (m/z) range of 50-442 with mass resolution at full-width half-maximum (FWHM) of 0.55 at m/z 91 and 0.80 at m/z 222. A solid-phase microextraction (SPME) fiber mounted in a simple syringe-style holder is used for sample collection and introduction into a specially designed low thermal mass GC injection port. This portable GC-TMS system weighs <13 kg (28 lb), including batteries and helium carrier gas cartridge, and is totally self-contained within dimensions of 47 X 36 X 18 em (18.5 X 14 X 7 in.). System start-up takes about 3 min and sample analysis with library matching typically takes about 5 min, including time for column cool-down. Peak power consumption during sample analysis is about 80 W. Battery power and helium supply cartridges allow 50 and 100 consecutive analyses, respectively. Both can be easily replaced. An on-board library of target analytes is used to provide detection and identification of chemical compounds based on their characteristic retention times and mass spectra. The GC-TMS can detect 200 pg of methyl salicylate on-column. n-Butylbenzene and naphthalene can be detected at a concentration of 100 ppt in water from solid-phase microextraction (SPME) analysis of the headspace. The GC-TMS system has been designed to easily make measurements in a variety of complex and harsh environments. and toxic industrial chemicals (TICs), is a concern, the ability to rapidly detect and accurately identify such chemicals in harsh environments is of great utility. There is a need for field-portable, selective, and sensitive detectors for military and emergency first-responder operations and for on-site environmental contamination measurement, to mention only a couple of key applications. The development of fieldportable devices directed toward fast, on-site analysis is one of the most active research areas in analytical chemistry.Currently, several approaches for detection of CWAs and TICs are utilized by military personnel, first responders, and environmental scientists. They include dye solubility (detection paper), enzymatic reaction,

We describe a novel radio frequency ion trap mass analyzer based on toroidal trapping geometry and microfabrication technology. The device, called the halo ion trap, consists of two parallel ceramic plates, the facing surfaces of which are imprinted with sets of concentric ring electrodes. Radii of the imprinted rings range from 5 to 12 mm, and the spacing between the plates is 4 mm. Unlike conventional ion traps, in which hyperbolic metal electrodes establish equipotential boundary conditions, electric fields in the halo ion trap are established by applying different radio frequency potentials to each ring. The potential on each ring can be independently optimized to provide the best trapping field. The halo ion trap features an open structure, allowing easy access for in situ ionization. The toroidal geometry provides a large trapping and analyzing volume, increasing the number of ions that can be stored and reducing the effects of space-charge on mass analysis. Preliminary mass spectra show resolution (m/Deltam) of 60-75 when the trap is operated at 1.9 MHz and 500 Vp-p.

A miniature ion trap mass analyzer is reported. The described analyzer is a 1/5-scale version of a previously reported toroidal radio frequency (rf) ion trap mass analyzer. The toroidal ion trap operates with maximum rf trapping voltages about 1 kV p-p or less; however despite the reduced dimensions, it retains roughly the same ion trapping capacity as conventional 3D quadrupole ion traps. The curved geometry provides for a compact mass analyzer. Unit-mass resolved mass spectra for n-butylbenzene, xenon, and naphthalene are reported and preliminary sensitivity data are shown for naphthalene. The expected linear mass scale with rf amplitude scan is obtained when scanned using a conventional mass-selective instability scan mode combined with resonance ejection. (J Am Soc Mass Spectrom 2006, 17, 916 -922)

In radiofrequency ion traps, electric fields are produced by applying time-varying potentials between machined metal electrodes. The electrode shape constitutes a boundary condition and defines the field shape. This paper presents a new approach to making ion traps in which the electrodes consist of two ceramic discs, the facing surfaces of which are lithographically imprinted with sets of concentric metal rings and overlaid with a resistive material. A radial potential function can be applied to the resistive material such that the potential between the plates is quadrupolar, and ions are trapped between the plates. The electric field is independent of geometry and can be optimized electronically. The trap can produce any trapping field geometry, including both a toroidal trapping geometry and the traditional Paul-trap field. Dimensionally smaller ion trajectories, as would be produced in a miniaturized ion trap, can be achieved by increasing the potential gradient on the resistive material and operating the trap at higher frequency, rather than by making any physical changes to the trap or the electrodes. Obstacles to miniaturization of ion traps, such as fabrication tolerances, surface smoothness, electrode alignment, limited access for ionization or ion injection, and small trapping volume are addressed using this design. analysis is accomplished using radiofrequency quadrupolar potentials in at least two dimensions. In the Paul trap, three hyperboloidal electrodes trap ions in all three dimensions. In the rectilinear and linear traps, DC potentials on end plates trap ions in the third dimension. In the toroidal ion trap, the two-dimensional trapping field forms a closed loop.In all ion trap variations, metal electrodes are used to produce the appropriate electric fields. For full-sized ion traps, modem machining equipment easily produces the hyperboloidal electrode surfaces of the quadrupole ion trap. For miniaturized traps, however, machining methods have been pushed to the limit, and simpler electrode geometries such as planar and cylindrical are required. For this reason, most miniaturized and microfabricated ion traps have utilized the cylindrical trap design [12,[16][17][18][19][20].The need for a portable mass spectrometer has largely driven efforts to produce miniaturized ion traps [21]. Although the mass analyzer is just one of several components of a complete mass spectrometer system, miniaturization of the mass analyzer can often reduce the size and weight of other components. For example, the amplitude of ion motion is reduced in a small ion trap, so the mean free path of ions can be smaller (or

This article presents a method of simulating molecular transport in capillary gas chromatography (GC) applicable to isothermal, temperature-programmed, and thermal gradient conditions. The approach accounts for parameter differences that can occur across an analyte band including pressure, mobile phase velocity, temperature, and retention factor. The model was validated experimentally using a GC column comprised of microchannels in a stainless-steel plate capable of isothermal, temperature-programmed, and thermal gradient GC separations. The parameters governing retention and dispersion in the transport model were fitted with 12 experimental isothermal separations. The transport model was validated with experimental data for three analytes using four temperature-programmed and three thermal gradient GC separations. The simulated peaks (elution time and dispersion) give reasonable predictions of observed separations. The magnitudes of the maximum error between simulated peak elution time and experiment were 2.6 and 4.2% for temperature-programmed and thermal gradient GC, respectively. The magnitudes of the maximum error between the simulated peak width and experiment were 15.4 and 5.8% for temperature-programmed and thermal gradient GC, respectively. These relatively low errors give confidence that the model reflects the behavior of the transport processes and provides meaningful predictions for GC separations. This transport model allows for an evaluation of analyte separation characteristics of the analyte band at any position along the length of the GC column in addition to peak characteristics at the column exit. The transport model enables investigation of column conditions that influence separation behavior and opens exploration of optimal column design and heating conditions.