Hewlett-packard Company

Agilent Technologies, Inc.

Robert P Rhodes

William H Wilson

Mahmoud F Abdel-Rahman

James W Baker

Steven J Engel

Leonid M Blumberg

William Bernard Trescott

Thomas E Price

George P Walsh

Michael D Glaser

Sammye E Miller

Terry A Woodruff

Roger A Brown

Thomas M Przybylski

Joseph Bush

Andrew J Murphy

Richard E Marsh

Ellen F Mason

An apparatus for receiving a chemical species is disclosed. The apparatus includes an emission block configured to receive a vapor phase chemical species that is excited by chemical reaction in the emission block to provide an excited species that emits light. The emission block has an interior portion having a surface. A coating is disposed over the surface and the coating reduces adsorption of the excited species onto the surface.

Chemiluminescent detector having coating to reduce excited species adsorption

A flame photometric detector (FPD) for use in a gas chromatography (GC) apparatus is described. The FPD has an emission block that is maintained in a first temperature range, and a transfer line that is maintained in a second temperature range that is greater than the first temperature range. The FPD is coupled to a light detector, such as a photomultiplier tube (PMT).

Flame photometric detector

A method for semi-automatically generating configuration information for a gas chromatograph uses an identification device reader of the gas chromatograph to 1) determine a presence and location of sample flow component identification devices in or on identification device holders that hold the sample flow component identification devices; 2) read information from sample flow component identification devices held in the identification device holders; and 3) output configuration information for the gas chromatograph. The configuration information is based on the presence and location of particular sample flow component identification devices in or on particular identification device holders, and on associations of particular identification device holders with particular sample flow component connections to the gas chromatograph. The configuration information indicates if and how sample flow components are connected to the gas chromatograph.

Gas chromatograph providing semi-automatic identification of connected sample flow components, and method of operating same

A system for synchronizing clock signals in an analytical device includes a first module including a timing command generator configured to generate a command signal, the command signal related to a master clock signal, and a second module including a command interpreter configured to generate a timing reference signal related to the command signal and a local clock signal. The second module includes a clock generator configured to receive the timing reference signal and the local clock signal and is configured to adjust a timing output of the second module so that the timing of the second module is synchronized to the master clock signal.

System for clock synchronization for modules in an analytical device

An inward opening oven intake for a gas chromatographic (GC) oven includes an inward opening intake flap that opens into the GC oven near the bottom of the GC oven. Opening at a flap angle, the inward opening intake flap creates a low-pressure region to draw a large amount of airflow into the GC oven during cool-down. In addition, the inward opening oven intake manipulates the airflow within the GC oven to more efficiently draw heat away from the oven walls. This greater efficiency allows for faster cycle time and higher sample throughput.

Inward opening oven intake for gas chromatographic oven

An electronic circuit and a method of generating an electrical discharge for an ionization detector system. The electronic circuit includes a transformer with a primary portion and a secondary portion. The circuit and method produce an electrical discharge across a set of electrodes. The discharge is stable over time and has relatively low peak currents associated therewith.

Enhancing the stability of electrical discharges

Chromatograph

A thermal conductivity detector includes a cavity wall defining a cavity for receiving a quantity of a sample fluid, the cavity wall being subject to a cavity wall temperature that is temporally and spatially variable, and a sensor located in the cavity and connected preferably in a bridge circuit configuration for providing a temperature sense signal. The sensor exhibits a resistance which is dependent on a temperature of the sensor. A first signal providing means includes reference means preferably in the form of first and second reference resistors located within first and second reference resistor cavities. The first and second reference resistors are connected to a reference voltage in a voltage divider network such that a node of the voltage divider network provides a temperature compensation signal that is representative of the average temperature of the cavity wall. Second signal providing means, connected to the balance nodes of the bridge circuit configuration, provide a temperature sense signal that is related to a change in resistance of the sensor resistor and thereby representative of the sensor temperature. The temperature compensation signal may optionally be conditioned by a voltage gain circuit and a voltage offset circuit to provide a temperature compensation signal. The temperature sense signal and the temperature compensation signal are provided to a third signal providing means wherein the temperature compensating signal is used to accurately compensate for changes in the temperature sense signal that are due to the temporal and/or spatial variations in the cavity wall temperature. In particular, the temperature compensation signal may represent an averaged value of at least two cavity wall temperatures, thus particularly compensating for the effect of a spatial temperature gradient in the cavity wall.

Compensation for spacial and temporal temperature variations in a

A thermal conductivity detector includes a cavity wall defining a cavity for receiving a quantity of the sample fluid, the cavity wall being subject to a cavity wall temperature, and a sensor located in the cavity and connected as a first element in a bridge circuit configuration. The sensor exhibits a resistance which is dependent on a temperature of the sensor. A variable resistor having a selectable resistance in response to a control signal is connected in the bridge circuit configuration as a second element. A signal providing means, connected to the balance nodes of the bridge circuit configuration, provides a first signal which is related to a change in resistance of the sensor and thereby representative of the sensor temperature. Means for sensing the temperature of the cavity wall provides a temperature sense signal to a controller, which in response provides a heating control signal to a cavity wall heating means. The controller also determines the cavity wall temperature and in response causes the variable resistor to achieve a selected resistance value that will cause the sensor resistance to change. The temperature of the sensor is thereby set so as to accurately and reliably establish a selectable, predetermined temperature differential between the sensor and the cavity wall.

Thermal conductivity detector

Analog-to-Digital Converter (A/D converter) consisting of several continuously integrating charge balancing (CB) conversion stages. During each conversion interval, all CB capacitors are discharged by a reference current. In each stage, the end of the discharge of the CB capacitor is detected by a zero crossing detector. Time intervals between the zero crossing events and corresponding discharge termination events represent time equivalents of quantization errors. Each stage, other than the first, converts the time equivalents of quantization errors of the previous stage. Output of the entire multistage A/D converter is combined from the outputs of all stages in a way which provides compensation of a quantization error of any stage by the output of the next stage. Quantization noise (sequence of quantization errors) of the entire A/D converter becomes the same as the N-time differenced (N-number of stages) quantization noise of the last stage. The differencing shapes spectral density of quantization noise in such a way that the largest portion of the noise energy becomes shifted outside of the signal bandwidth. The larger the number of stages, the smaller the in-band portion of the quantization noise. The out-of-band portion of quantization noise can be filtered out in the post-conversion digital signal processing.

Analog-to-digital converter

A method and apparatus for controlling measurement repeatability in spectrochemical analysis which analysis utilizes a plasma source is shown to include a plasma generator for providing energy to the plasma source to sustain plasma, a sensor for sensing the operating temperature of the plasma generator and a temperature controller for controlling the operating temperature of the plasma generator in response to the temperature sensed by the sensor. The temperature controller controls the operating temperature of the plasma generator either within a temperature range, such as between 100.degree. C. or at a set point temperature. In the case of a magnetron having heat conductive fins as the plasma generator, the sensor senses the temperature of at least one of said fins and the temperature controller includes a fan directed to move air across the fins and a speed controller for controlling the speed of the fan in response to the sensed temperature of the fins.

Method and apparatus for spectrochemical analysis having maximum

Apparatus for igniting a flame ionization detector wherein means are provided for gradually reducing the flow of oxygen to the jet in response to a sudden increase in the temperature at a point downstream from the jet and wherein normal oxygen flow is restored after the temperature decreases to an operating value.

Automatic ignition system for a flame ionization detector

An analog-to-digital converter system is disclosed in which the amplitude of the signal is compressed by means including a logging means prior to an analog-to-digital converter. Reference signals of known values are applied to the logging means and their values at the output of the converter are used to determine a linearity factor which is applied to a multiplier coupled to the output of the converter. The amplitude of one of the reference signals at the output of the multiplier is compared with what it should be and the difference is added by an adder at the output of the multiplier.

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Lincoln University, PA, United States of America

Robert P Rhodes