Abstract: Disclosed is quadrupole ion trap mass spectrometer of the type including a ring electrode and end caps defining a trap volume and including means for introducing sample ion into the ion trap and means for applying voltages to the electrodes. Further included are means for applying two resonant excitation waveforms at two different frequencies and two different voltages between the end cap electrodes to simultaneously excite multiple ions in the ion trap volume.

Abstract: An electrospray ion source having a capillary tube for directing ions from an ionizing region to an analyzing region including a skimmer in which the capillary tube is oriented to cause undesolvated droplets to strike the skimmer.

Abstract: An electrospray interface apparatus is disclosed. The apparatus includes an inner needle for transferring a liquid sample to an ionizing region at one end of the needle. A first outer tube surrounds and is spaced apart from the needle to form a cylindrical space through which a flowing liquid may pass. The tube has one end extending beyond the end of the needle to define a mixing volume where the sample and liquid can mix. A second outer tube surrounds the first tube to define a second cylindrical space for flowing a gas past the end of the first tube and needle to focus the electrospray. A voltage is also provided between the tips of the needle and the tubes and an adjacent surface.

Abstract: Disclosed is a multi-stage particle separator for separating analyte from non-analyte solvent in a fluid sample having nebulizing means to form droplets from the liquid sample and means coupled to the nebulizing means for adding helium to the nebulizing means. Furthermore, the multi-stage particle separator has a desolvation chamber for receiving the droplets, the desolvation chamber terminating in a nozzle, a multi-stage momentum separator including skimmers, and means for introducing a gas into one or more of the states to increase pressure of the latter stage so that the particles leave the multi-stage separator substantially free of solvent.

Abstract: This invention relates generally to a method of operating an ion trap mass spectrometer to determine the resonant excitation frequencies of trapped ions. This can be achieved by: (1) introducing sample ions into the ion trap volume: (2) adjusting the trapping fields so that parent ions having a mass-to-charge ratio of interest which are to undergo collision induced dissociation (CID) are trapped; (3) applying an excitation voltage of predetermined frequency and amplitude across the end caps of the ion trap; (4) scanning the frequency of the excitation voltage in a first direction and monitoring for ejection of the parent ions; (5) repeating steps (1) through (3) and scanning the frequency of the excitation voltage in an opposite direction and monitoring for ejection of the parent ions; (6) averaging the frequencies at which the ions are ejected; and (7) applying that frequency in a subsequent MS/MS scan to promote CID of the parent ions to form daughter ions.

Abstract: An electrospray ion source in which the liquid sample is sheathed with a sheath liquid which reduces the formation of water droplets and minimizes formation of high energy neutrals, resulting in improved signal-to-noise ratios.

Abstract: An improved method of mass analyzing a sample in a three-dimensional quadruple ion trap with varying fields is disclosed. The dynamic range and sensitivity of previous methods is increased by controlling the number of sample ions formed in the ion trap to avoid saturation and space charge.

Abstract: Apparatus and method for mass analysis with improved resolution in an r.f.-only multipole mass spectrometer by use of a supplemental r.f. field which resonantly renders ions unstable. Further, the r.f. field is frequency modulated and the output signal demodulated for mass analysis.

Abstract: This invention relates generally to a quadrupole ion trap mass spectrometer and method of operation and more particularly to an ion trap mass spectrometer in which pulses of energy of predetermined frequencies are applied across the end caps to independently and sequentially excite ions of different masses trapped in the ion trap to perform parent scanning, neutral loss scanning and selected reaction monitoring.

Abstract: A chemical mixture is conveyed to a multiple charging apparatus, where multiply charged ions are formed. The multiply charged ions are then conveyed to a mass spectrometer which generates mass/charge spectrum data relating intensity to a range of mass/charge values. This mass/charge spectrum data is transformed to generate mass spectrum data relating intensity to a range of mass values. Thereafter, a set of known masses are identified from the mass spectrum data by associating each peak intensity value in the spectrum with its molecular mass. Then a list of mass/charge ratios for each of the identified masses is formed and stored. Next, a range of mass/charge ratios for each mass value of the mass spectrum data is computed.

Abstract: A chromium or oxidized chromium surface for use in sample analyzing and ionizing apparatus, such as an ion trap or ionization chamber, which does not degrade or decompose a sample in contact with the surface.

Abstract: A mass spectrometer including at least one mass analyzer into which an ion beam to be analyzed is projected having a collision surface means in-line with the ion beam to form surface collision products which are directed into the in-line mass analyzer.

Abstract: A multiple rod assembly for multipole mass spectrometers in which the rods are supported in cooperative aligned relationship by ceramic rings with metal rings and brackets.

Abstract: A transfer line used between a gas chromatograph and an ion source of a mass spectrometer is constructed with an inner tube, a middle tube and an outer tube. Disposed within the middle tube are a heater unit which extends along the middle tube and a sensor well. The remaining air space in the middle tube is filled with compacted fine thermally conductive powder. Thermal insulation is provided between the middle and outer tubes. End seals are provided to maintain the integrity of the vacuum system of the mass spectrometer.

Abstract: Method and apparatus for controlling an instrument which can perform a specified cyclic process. The instrument's process is controlled by a computer which has two concurrently defined tasks: an operator task for running an instrument control program, and a compiler task for compiling new instrument control programs input by the instrument's user. The currently running program is suspended and a new program's execution is begun when (a) a new program has been successfully compiled by the compiler, and (b) the current program is about to perform a jump back at the end of an instruction loop. When a main instrument control program finishes executing, a new program is run if a new program has been successfully compiled; otherwise, execution of the most recently suspended program resumes. Thus a newly compiled program interrupts the currently running program only between instruction loops, and only as long as necessary to execute its instructions.

Abstract: The method of isolating ions of single mass or narrow range of masses in a three-dimensional ion trap comprising ionizing a sample in the trap at a low RF voltage, increasing the RF voltage and applying a DC voltage whereby to eject unwanted ions while isolating ions of said single mass or narrow range of masses.

Abstract: An unbalanced radio frequency voltage is supplied between two pairs of conductive rods of a quadrupole mass filter of a mass spectrometer system. Means are provided for d.c. voltage polarity reversal for monitoring positive and negative ions. The d.c. voltage is derived by rectification of the radio frequency voltage.

Abstract: A method is disclosed for increasing the dynamic range and sensitivity of a quadrupole ion trap mass spectrometer operating in the chemical ionization mode. Prior to mass analysis, a prescan is performed with the ion trap and the ionization and reaction periods are adjusted to produce enough stored product or analyte ions to generate a good signal-to-noise ratio in the detection of trace amounts of analyte, yet not so many analyte ions that resolution in the mass spectrum is lost. A mass analysis scan is then performed with the ion trap using the ionization and reaction periods predetermined during the prescan.

Abstract: .[.A negative ion detector converts negative ions to positive ions by means of a conversion anode which is maintained at a relatively high positive voltage. The resultant positive ions are detected by a standard continuous dynode electron multiplier which has its detection signal output at ground potential..]. .Iadd.Apparatus for detecting the abundance of negative ions from a source of negative ions, having a first conversion dynode and an electron multiplier, the electron multiplier having a second conversion dynode. The first conversion dynode is operated at a high positive potential to attract the negative ions whereby the negative ions impact the first conversion dynode with a substantial portion of the negative ions being converted to secondary positive ions.

Abstract: A simple and economical method of mass analyzing a sample by means of a quadrupole ion trap mass spectrometer in an MS/MS mode comprises the steps of forming ions within a trap structure, changing the RF and DC voltages in such a way that the ions with mass-to-charge ratios within a desired range will be and remain trapped within the trap structure, dissociating such ions into fragments by collisions and increasing the field intensity again so that the generated fragments will become unstable and exit the trap volume sequentially to be detected. A supplementary AC field may be applied additionally to provide various scan modes as well as dissociate the ions.