Abstract: In a mass spectrometer, typically a quadrupole, one of the rod sets is constructed to create an axial field, e.g. a DC axial field, thereon. The axial field can be created by tapering the rods, or arranging the rods at angles with respect to each other, or segmenting the rods, or by providing a segmented case around the rods, or by providing resistively coated or segmented auxiliary rods, or by providing a set of conductive metal bands spaced along each rod with a resistive coating between the bands, or by forming each rod as a tube with a resistive exterior coating and a conductive inner coating, or by other appropriate methods. When the axial field is applied to Q0 in a tandem quadrupole set, it speeds passages of ions through Q0 and reduces delay caused by the need to refill Q0 with ions when jumping from low to high mass in Q1. When used as collision cell Q2, the axial field reduces the delay needed for daughter ions to drain out of Q2.

Abstract: A method of analyzing a protein, namely determining the amino acid sequence of a protein is described. Trypsin is added to a protein to form a liquid phase mixture of trypsin and the protein. The disulfide linkages of the protein may be reduced and the resulting sulfhydryl groups alkylated either before or after the addition of trypsin. The trypsin is allowed to digest the protein long enough to cleave protein into tryptic fragments. A portion of the digested mixture is ionized by ion evaporation to produce gas phase ions of the tryptic fragments, the gas phase ions being predominantly doubly charged with one charge at each end of the doubly charged ions. The gas phase ions of the tryptic fragments are analyzed by sequentially selecting therefrom ions of a desired mass to charge ratio in a first mass analyzer. The selected ions are fragmented by collision in a second mass analyzer to produce daughter ions, and the daughter ions are then analyzed in a third mass analyzer.

Abstract: A torch for Inductively Coupled Plasma Spectrometry (ICPS) is formed from quartz and has inner and outer tubes defining an annular channel. The end of the inner tube is within an end portion of the outer tube, to define a chamber for a plasma ball. An inlet for a main gas flow opens tangentially into the annular channel. The annular channel is configured so as to maximize the swirl component of this flow. To this end, a connection to the inlet is provided with an annular toroidal shape, having a cross-section to or larger than the inlet. Further, the inlet is mounted relatively close to the end of the inner tube, so as to minimise decay of the swirl component as the gas flows along the annular channel, the length of the annular channel being sufficient to ensure that the flow leaving the annular channel is uniform and has a uniform swirl component.

Abstract: In high volume laboratory analysis of patient medical specimens, control materials are inserted at periodical intervals (e.g. once per eight hours) and analyzed. If the results of the analysis deviate from the mean according to statistical rules, the run of analyses prior to the insertion of control materials has in the past been rejected, often causing a substantial loss of results because the control materials were not inserted sufficiently frequently. According to the invention the patient mean of a test is determined, and when the mean deviates from the predetermined mean by more than a selected amount, this determination is used, not to reject the run, but rather to trigger insertion and analysis of control materials. If the analysis of control materials shows that the run is in control, the analyses made prior thereto are reported and the run is resumed. If the control material analysis shows that the run is out of control, then the prior analyses are rejected.

Abstract: A mass analyzer having a set of rods, e.g. quadrupole rods, into which ions are injected axially and are then contained by the combination of collision gas in the volume between the rods and end lenses which prevent the ions from leaving the volume between the rods. After the ions have been contained and manipulated, they are ejected radially through an opening or slot in one of the rods for detection. The configuration provides many of the advantages of a conventional ion trap, e.g. greater sensitivity, while avoiding a number of disadvantages of a conventional trap. If desired ions can be dissociated by applying an axial oscillating field, before being radially ejected.

Abstract: A method of analyzing an analyte contained in a plasma, in inductively coupled plasma mass spectrometry (ICP-MS). A sample of the plasma is drawn through an orifice in a sampler, then skimmed in a skimmer orifice, and the skimmed sample is directed at supersonic velocity onto a blunt reducer having a small orifice therein, forming a shock wave on the reducer. Gas in the shock wave is sampled through an offset aperture in the reducer into a vacuum chamber containing ion optics and a mass spectrometer. This reduces space charge effects, thus reducing mass bias and also reducing the mass dependency of matrix effects. Since the region between the skimmer and the reducer can operate at about 0.1 Torr, which is the same pressure as that produced by the roughing pump which backs the high vacuum pump for the vacuum chamber, a single common pump can be used for both purposes, thus reducing the hardware needed.

Abstract: A mass analyzer system uses a simultaneous mode electron multiplier detector which outputs both a pulse count and an analog signal. Depending on the ion flux intensity, the signals define a pulse count only region in which the pulse count only signal is valid, an overlap region in which both the pulse count and analog signals are valid, an analog signal only region in which only the analog signal is valid, and a neither analog nor pulse region in which neither signal is valid. The system produces a separate flag for each region. When a mass spectrum is scanned, for each dwell the pulse count and analog data are recorded together with their associated flag and are placed in memory. The signals, with the flags, can then be used to produce a mass spectrum using the pulse count only signal, the analog only signal, or both.

Abstract: Liquid from a liquid chromatograph or other sample source, preferably assisted by a high velocity coaxial gas jet, is sprayed through a capillary tube producing a flow in a first direction of charged droplets. A flow of heated gas, in a second direction different from the first direction, intersects the droplet flow at a region upstream of an orifice. The flows mix turbulently, with the second flow helping to evaporate the droplets to produce ions and helping to move the evaporating droplets toward the orifice, providing a focusing effect. Ions are drawn through the orifice into a mass analyzer and analyzed. Alternatively the flows of liquid and heating gas can be directed toward each other and at right angles to the axis through the orifice, and the inhaling effect of the orifice can be used to draw droplets toward it, or a third gas flow can be used for this purpose. The heated intersecting gas flow typically provides an increase in sensitivity (ion counts per second) of between 10 and 100 times.

Abstract: A liquid sample to be analyzed is fed to a micro pump. The pump directs the solution, as a stream of uniformly sized and spaced droplets, into a laminarly flowing stream of hot carrier gas. The carrier gas evaporates the solvents (e.g. water) in the droplets to form a stream of dried particles. The particles are vaporized by a plasma, laser or other heat source. The vapour can be ionized and the ions analyzed by a mass spectrometer, or the vapour can be analyzed by optical spectroscopy. The method reduces oxide and other interference effects, increases sample utilization, and reduces waste, signal noise, and memory effects, increasing instrument productivity. Multiple nozzles can be used to change samples or to shoot calibrating droplets, further increasing productivity. Signal detection can be synchronized with droplet firing, or the signal, which is intrinsically modulated at the drop frequency, can be band pass filtered and synchronously detected, to increase the signal to noise ratio.

Abstract: A method is provided of increasing the resolution in a tandem mass spectrometer having a first quadrupole Q1 to select a parent ion, a second quadrupole Q2 which contains a target gas and forms a collision cell, and a third or analyzing quadrupole Q3 which generates a mass spectrum from daughter ions from Q2. In the method, the target thickness of the target gas in Q2 is held at least at 1.32.times.10.sup.15 cm.sup.-2, preferably at least 3.30.times.10.sup.15 cm.sup.-2, and the DC offset voltage between Q2 and Q3 is kept low or zero. This greatly improves the resolution available in Q3. Q3 is therefore operated with at least unit resolution, and in some cases with resolution of 1/2 or 1/3 amu, making it possible to resolve isotopes of singly, doubly or triply charged daughter ions.

Abstract: A two dimensional RF multipole field formed by a set of parallel rods, e.g. quadrupole rods, serves as an inlet for an ion trap. The field both accepts and stores ions for the trap, and rejects unwanted ions, while the trap is performing an analysis. This greatly increases the duty cycle of the overall system, increasing the system sensitivity.

Abstract: In a mass spectrometer system, ions travel through an orifice in an inlet plate into a first vacuum chamber containing AC-only rods, and then through an orifice into a second vacuum chamber containing a standard quadrupole. The second vacuum chamber is held at low pressure, e.g. 0.02 millitorr or less, but the product of the pressure in the first chamber times the length of the AC-only rods is held above 2.25.times.10.sup.-2 torr cm, preferably between 6.times.10.sup.-2 and 15.times.10.sup.-2 torr cm, and the DC voltage between the inlet plate and the AC-only rods is kept low, e.g. between 1 and 30 volts, preferably between 1 and 10 volts. This produces a large enhancement in ion signal, with less focussing aberration and better sensitivity at high masses, and also allows the use of smaller, cheaper pumps so the system can be more easily transportable.

Abstract: A disposable plastic cartridge contains three fine lightweight wire mesh collectors, each of phosphor bronze. One collector has an oxidized surface for collecting drug particulates. The other two have surfaces electroplated with zinc to form a rough multi-fissured surface for trapping low volatility vapors. In use, a portion of a warm sample air stream is chilled and passed through the collectors in parallel for sample collection. Simultaneously part of the sample air stream by-passes the chiller and is fed directly into a mass analyzer for real time analysis. Next, both collection and real time analysis are terminated, and each collector is desorbed in sequence with a pulse of hot air which flows into the mass analyzer for sequential analysis.

Abstract: A mass analyzer in which an ion signal, typically from a plasma, travels through an orifice into a vacuum chamber, and through a focussing system in the vacuum chamber into a mass spectrometer and ion detector. Drift of the detected ion signal, and differences in drift of the detected ion signal for different elements, are greatly reduced by a small shadow stop placed in the vacuum chamber immediately behind the orifice. The shadow stop and plate containing the orifice are both preferably grounded. The focussing system includes a Bessel box lens, and drift is further reduced by insulating the stop in the Bessel box lens from the barrel and biasing the Bessel stop differently from the barrel.

Abstract: A plasma generated within an induction coil is sampled through a sampler orifice into a first vacuum chamber stage and then through a skimmer orifice into a second vacuum chamber stage for mass analysis of trace ions in the plasma. Arcing at the orifices is reduced or prevented by applying, to the plates containing the orifices, an RF bias voltage derived from the generator which powers the coil. Since optimum ion transmission is highly dependent on the phase and amplitude of the RF bias, phase and amplitude adjustment networks are provided to optimize the ion count. Alternatively, arcing at the sampler orifice can be eliminated by grounding the induction coil at or near its center and the RF bias can be applied only to the plate containing the skimmer orifice.

Abstract: A plasma is generated within an induction coil and the plasma is sampled through an orifice into a vacuum chamber for mass analysis of trace ions in the plasma. Arcing at the orifice is prevented by grounding the induction coil at or near its center, thus eliminating ultraviolet noise and reducing average ion energies and ion energy spread, as well as preventing destruction of the orifice. The elimination of arcing at the orifice allows the use of a sharp edge orifice structure to prevent formation of a cool boundary layer over the orifice and also permits direct sampling of the plasma. The direct sampling and the lack of cooling prevent recombination and reaction of the ions with oxygen and improve the response to elements of high ionization potential, increasing the desired ion signal and greatly reducing the presence of oxides which would otherwise complicate the spectrum.