Abstract: In various aspects, ion sources, mass spectrometer systems, and a power supply circuit coupled to a feedback circuit are provided. A power supply is provided that includes at least the power supply circuit and is operable to transfer charge to a load. The feedback circuit is responsive to a DC component of an output voltage supplied by the power supply in a first feedback loop and an AC component of the output voltage in a second feedback loop to produce a feedback signal representative of at least one of: a value of the output voltage before a charge transfer from a capacitor of the power supply to a load; the value of the output voltage during the charge transfer from the capacitor of the power supply to the load; or the value of the output voltage after the charge transfer from the capacitor of the power supply to the load.

Abstract: In various aspects, ion sources, mass spectrometer systems, and a power supply circuit coupled to a feedback circuit are provided. A power supply is provided that includes at least the power supply circuit and is operable to transfer charge to a load. The feedback circuit is responsive to a DC component of an output voltage supplied by the power supply in a first feedback loop and an AC component of the output voltage in a second feedback loop to produce a feedback signal representative of at least one of: a value of the output voltage before a charge transfer from a capacitor of the power supply to a load; the value of the output voltage during the charge transfer from the capacitor of the power supply to the load; or the value of the output voltage after the charge transfer from the capacitor of the power supply to the load.

Abstract: Disclosed are methods and apparatus for compensating for mass error for a time-of-flight mass spectrometer. A reference flight distance for a pulse of ions corresponding to a reference temperature of one or more components of an ion flight path assembly is determined, and the temperature of one or more components of the ion flight path assembly is measured. Correlating the thermal expansion of the flight path assembly with the temperature measurement allows the measured flight times to be adjusted to correspond with the reference flight distance to thereby compensate for the thermal expansion of the flight path assembly. A mass spectrum is obtained using the adjusted flight times. In various embodiments, the temperature signal is used with pre-determined thermal expansion correction factors for the flight path assembly to calculate a correction factor to control another component of the TOF MS, such as the voltage applied to a power supply system or a signal to control clock frequencies.

Abstract: Disclosed is a method of determining when to calibrate a time-of-flight mass spectrometer. In various embodiments, the method comprises storing within a controller a set of parameters for the mass spectrometer; providing an updated set of parameters while retaining at least one set of previously stored parameters; computing at least one rate of change of the updated set of parameters with respect to the at least one set of previously stored parameters; and determining when to calibrate the mass spectrometer from the results of computing the rate of change of at least one of the parameters. In various embodiments, a parameter stored can be a set of temperatures derived from obtaining system temperature measurements of those components whose changing temperature is an indication of mass drift.

Abstract: In various aspects, ion sources, mass spectrometer systems, and a power supply circuit coupled to a feedback circuit are provided. A power supply is provided that includes at least the power supply circuit and is operable to transfer charge to a load. The feedback circuit is responsive to a DC component of an output voltage supplied by the power supply in a first feedback loop and an AC component of the output voltage in a second feedback loop to produce a feedback signal representative of at least one of: a value of the output voltage before a charge transfer from a capacitor of the power supply to a load; the value of the output voltage during the charge transfer from the capacitor of the power supply to the load; or the value of the output voltage after the charge transfer from the capacitor of the power supply to the load.

Abstract: Disclosed is a method of determining when to calibrate a time-of-flight mass spectrometer. In various embodiments, the method comprises storing within a controller a set of parameters for the mass spectrometer; providing an updated set of parameters while retaining at least one set of previously stored parameters; computing at least one rate of change of the updated set of parameters with respect to the at least one set of previously stored parameters; and determining when to calibrate the mass spectrometer from the results of computing the rate of change of at least one of the parameters. In various embodiments, a parameter stored can be a set of temperatures derived from obtaining system temperature measurements of those components whose changing temperature is an indication of mass drift.

Abstract: Disclosed are methods and apparatus for compensating for mass error for a time-of-flight mass spectrometer. A reference flight distance for a pulse of ions corresponding to a reference temperature of one or more components of an ion flight path assembly is determined, and the temperature of one or more components of the ion flight path assembly is measured. Correlating the thermal expansion of the flight path assembly with the temperature measurement allows the measured flight times to be adjusted to correspond with the reference flight distance to thereby compensate for the thermal expansion of the flight path assembly. A mass spectrum is obtained using the adjusted flight times. In various embodiments, the temperature signal is used with pre-determined thermal expansion correction factors for the flight path assembly to calculate a correction factor to control another component of the TOF MS, such as the voltage applied to a power supply system or a signal to control clock frequencies.

Abstract: In various aspects, ion sources, mass spectrometer systems, and a power supply circuit coupled to a feedback circuit are provided. A power supply is provided that includes at least the power supply circuit and is operable to transfer charge to a load. The feedback circuit is responsive to a DC component of an output voltage supplied by the power supply in a first feedback loop and an AC component of the output voltage in a second feedback loop to produce a feedback signal representative of at least one of: a value of the output voltage before a charge transfer from a capacitor of the power supply to a load; the value of the output voltage during the charge transfer from the capacitor of the power supply to the load; or the value of the output voltage after the charge transfer from the capacitor of the power supply to the load.

Abstract: A tandem time-of-flight mass spectrometer is described. The spectrometer includes a pulsed source of ions that focuses a packet of ions substantially within a predetermined mass-to-charge ratio range onto a focal plane in a flight path of the ions. An ion selector receives the focused packet of ions and selects ions substantially within the predetermined mass-to-charge ratio range and rejects substantially all other ions. An ion fragmentor that fragments a fraction of the selected ions is positioned in the flight path of the selected ions. A pulsed ion accelerator that accelerates the selected ions and fragments thereof is positioned in a flight path of the selected ions and fragments thereof after the ion fragmentor. An electrode is positioned in the flight path of the accelerated selected ions and fragments thereof after the pulsed ion accelerator. In operation, the electrode is biased with a time varying bias voltage that increases the energy of the fragments relative to the selected ions.

Abstract: A tandem time-of-flight mass spectrometer is described. The spectrometer includes a pulsed source of ions that focuses a packet of ions substantially within a predetermined mass-to-charge ratio range onto a focal plane in a flight path of the ions. An ion selector receives the focused packet of ions and selects ions substantially within the predetermined mass-to-charge ratio range and rejects substantially all other ions. An ion fragmentor that fragments a fraction of the selected ions is positioned in the flight path of the selected ions. A pulsed ion accelerator that accelerates the selected ions and fragments thereof is positioned in a flight path of the selected ions and fragments thereof after the ion fragmentor. An electrode is positioned in the flight path of the accelerated selected ions and fragments thereof after the pulsed ion accelerator. In operation, the electrode is biased with a time varying bias voltage that increases the energy of the fragments relative to the selected ions.

Abstract: A tandem time-of-flight mass spectrometer is described. The spectrometer includes a pulsed source of ions that focuses a packet of ions substantially within a predetermined mass-to-charge ratio range onto a focal plane in a flight path of the ions. An ion selector receives the focused packet of ions and selects ions substantially within the predetermined mass-to-charge ratio range and rejects substantially all other ions. An ion fragmentor that fragments a fraction of the selected ions is positioned in the flight path of the selected ions. A pulsed ion accelerator that accelerates the selected ions and fragments thereof is positioned in a flight path of the selected ions and fragments thereof after the ion fragmentor. An electrode is positioned in the flight path of the accelerated selected ions and fragments thereof after the pulsed ion accelerator. In operation, the electrode is biased with a time varying bias voltage that increases the energy of the fragments relative to the selected ions.

Abstract: An interface apparatus for introducing a sample for analysis from a liquid flow into a mass spectrometer as a plurality of charged droplets is disclosed. The interface apparatus includes interface body which defines a spray chamber and an orifice, a spray means defining a liquid-flow inlet channel and an excess-sample-flow exit channel and having an open end disposed inside the spray chamber, and a voltage device for applying a voltage to the sample to form a plurality of charged droplets. The charged droplets pass through the orifice in the interface body and are introduced into a mass spectrometer for analysis. The interface includes a valve for regulating the flow of sample into the sample inlet channel and a device for imposing a pressure gradient on the sample at the open end which induces the sample to flow from the sample inlet channel through the excess sample outlet channel.

Abstract: A system and process for analyzing a liquid sample is disclosed which includes an ultrasonic nebulizer capable of vibrating at a frequency between about 50 Khz and 760 Khz for converting the liquid sample to a liquid aerosol. The liquid aerosol is heated at a pressure of at least atmospheric pressure to evaporate solvent in the aerosol and to form a solid aerosol. The solid aerosol is separated from the evaporate solvent and the solid aerosol is directed into an electron impact ionizer and a mass spectrometer where it is analyzed.

Abstract: A gear pump is used for the primary flow source for a low pressure, high performance separation system. The pump is controlled such that its flow and leakage characteristics are compensated by an electronic controller which results in controlled output flow rates to a variety of loads. The pump is particularly suited for use in liquid chromatography (LC) systems, especially LC systems which use membrane based separation media. A modification to the gear pump results in an efficient mixer, further enhancing its use in LC systems which involve gradient operational modes. Also disclosed are embodiments which allow the gear pump to be used in high pressure separation systems, e.g., high performance liquid chromatography (HPLC) systems.

Abstract: An automatic incremental focusing scanner system which optically reads a code pattern on an object. The system includes a scanner which directs a beam of radiation onto the object at one of a number of focal lengths. The system further includes a range determining unit for measuring the range of the object relative to the scanner, and a mechanism for alternating the focal length of the radiation beam to selectively focus it as commanded by a control module. The focal length of the beam is adjusted based on the measured range to enable accurate reading of the code pattern.