Abstract: In a near infrared absorbance measurement instrument, an attenuated internal reflectance probe comprises a quartz rod having an inexpensive low purity central core surrounded by two high purity quartz layers. Narrow band infrared light is transmitted axially through the outer layer to cause the light to undergo total internal reflection from the inner and outer surfaces of the outer layer. A near infrared light detector measures the light transmitted through the outer layer to obtain a measurement of the absorbance of the fluid in contact with the outer surface of the outer layer without any interference from suspended particles or bubbles in the fluid being measured.

Abstract: An apparatus for measuring the BTU content of a gas includes a source of combustion air, a detector and a sample loop or tube connected to a six-port switching valve. The switching valve allows accurate and repeatable quantities of the gas to be obtained and mixed with the combustion air. In a second embodiment, the apparatus includes a second switching valve to obtain samples of the gas at a second pressure and calculate the BTU content at the second pressure. By measuring the BTU content at two different pressures, a quantity related to the volumetric flow of the gas between the two pressures can also be calculated.

Abstract: A method and apparatus for the measurement of the total organic carbon (TOC) content of a liquid is shown. The inorganic carbon in the liquid is converted into carbon dioxide and removed from it. At the same time, oxygen is added to the liquid. The liquid is then exposed to ultraviolet radiation and the organic carbon thereby oxidized. This oxidized carbon, in the form of carbon dioxide, is allowed to migrate across a gas-permeable, liquid-impermeable membrane directly into a measurement chamber, where its absorption of radiation is measured to determine its concentration.

Abstract: A measuring probe measures a parameter with a sensor. The sensor provides a sensor output signal related to a measured value. An amplifier section receives the sensor output signal and provides an amplifier output signal. An integrator has an input and an integrator output related to an integration of the input. Switching circuitry receives the amplifier output signal and a reference signal and has an output connected to the input of the integrator. Controller circuitry coupled to the switching circuitry connects the amplifier output to the integrator input during a sampling time, and the reference signal to the integrator input during a conversion time. The conversion time is related to the sensor output signal and is measured to obtain a digital representation of the sensor output.

Abstract: In the system for analyzing aqueous samples, the aqueous sample is deposited upon a sheet of filter paper which is held in a filter holder by clamping the peripheral edges of the filter paper between male and female threaded members of the filter holder. The filter paper with the sample is dried by a heated air stream directed perpendicularly toward the paper so that it flows around and through the paper. After the sample has been dried, it is analyzed by near infrared spectral analysis to measure the constituents of the dried sample.

Abstract: A micromachined mass spectrometer includes an ionizer, a separation region and a detector. The ionizer is formed from an upper electrode, a center electrode and a lower electrode. Ionization of a sample gas takes place around an edge of the center electrode. Accelerating electrodes extract ionized particles from the ionizer. Ionized particles are accelerated through the separation region. A magnetic field is applied in a direction perpendicular to travel of the ionized particles through the separation region causing the trajectory of the ionized particles to bend. The mass spectrometer is formed using micromachined techniques and is carried on a single substrate.

Abstract: A device and method for testing for Cystic Fibrosis includes a sample cell having a capillary tube with a lumen that will hold approximately five microliters of sweat. The capillary tube has metallic rings around each end of the tube with an RF oscillator attached to one ring and a microprocessor attached to the other. An RF signal, which is transmitted from the RF oscillator through the sweat in the sample cell, is subsequently analyzed at the microprocessor by comparing the transmitted signal to a reference. In accordance with the comparison made by the microprocessor, the presence of Cystic Fibrosis may be detected.

Abstract: A flow cell for use in optical measuring systems particularly suited for use with liquid food products is provided. The flow cell is manufactured from a single unitary piece of synthetic resin which is transparent to light in the near infrared range. Because the flow cell is constructed from a single piece, the interior surface is continuous and the presence of undesirable cracks or crevices is avoided.

Abstract: The photometer of the present invention includes an optical system in which an emission beam generated by pulsed ultra violet radiation from a source is split into a sample beam and a reference interference beam by spectrally selective mirrors arranged in series. These mirrors reflect a beam having a wavelength range corresponding to an absorption wavelength of the gas to be detected onto one solid state detector and to pass a beam to a second spectrally selective mirror where a beam having second range of wave lengths corresponding to an interfering gas is reflected onto a second solid state detector. This second beam serves to measure the interfering gas and also as an imperfect reference channel. In a preferred embodiment the radiation from the source is split prior to entering the sample cell.

Abstract: An automated cold vapor mercury assay system includes a sample inlet, a storage chamber of predetermined volume for storing a sample of material to be analyzed, a reaction chamber having first and second inlet ports and an outlet port, a reducing agent reservoir, a transport liquid reservoir, a distributor coupled to the sample storage chamber and movable between a first position connecting the storage chamber to the sample inlet and a second position connecting the storage chamber to the reaction chamber, analyzer apparatus coupled to the outlet port of the reaction chamber structure, and controller structure.

Abstract: A method and apparatus are disclosed for measuring a resistance of a sensor. The apparatus injects a first test current into the sensor and then measures a substantially stable first voltage level across the sensor when the first test current is present. The apparatus then injects a second test current into the sensor, the second test current being substantially equal to but opposite in polarity to the first test current. A substantially stable second voltage level across the sensor is measured when the second test signal is present. Using the first measured voltage level and the second measured voltage level, the apparatus calculates the resistance of the sensor.

Abstract: An immersion probe (for powder or liquid) is disclosed comprising an ATR element supported at the bottom of a radiation-confining tube. The ATR element has a sample-entering tip which is either conical (preferably) or roof-top shaped. The ATR element causes entering radiation to be reflected twice by its sample-engaging surfaces, where attenuation due to the sample material occurs. The ATR element also acts as a retroreflector, causing the exiting radiation to follow a path parallel to the entering radiation. In order to avoid spurious results due to reflection by the rear surface of the ATR element, its rear surface is cone shaped or rooftop shaped, using a large apex angle.

Abstract: A sparging-infrared liquid analyzing system having a vessel in which a gas stream makes a single pass through a liquid stream containing contaminants, in order to provide vapor-to-liquid equilibrium of contaminants in the gas stream. The gas stream is then passed through a condenser, in which the gas temperature is precisely controlled, and the gas is cooled to a point below the dew point of water vapor in the gas stream. The gas is then flowed into a gas cell for infrared analysis. Water vapor effects are removed from the analytical output. Also, the effects of excessive depletion of relatively insoluble contaminants are removed from the analytical output.

Abstract: A probe for liquid sample analysis is disclosed which causes radiation to pass through the sample at a gap formed in the probe housing. A single radiation transmission is used to avoid problems of radiation back scatter and sample reliability. Windows are provided on opposite sand and and and and and and ides of the gap to accommodate the shape of the beam in the gap, which may either be collimated, or focused in the gap. A retroreflector may be used to reverse the radiation direction in the probe. The light to and from the probe is preferably transmitted by optical fiber cables. Within the probe, light guides other than optical fibers may be used.

Abstract: A micromachined mass spectrometer includes an ionizer, a separation region and a detector. The ionizer is formed from an upper electrode, a center electrode and a lower electrode. Ionization of a sample gas takes place around an edge of the center electrode. Accelerating electrodes extract ionized particles from the ionizer. Ionized particles are accelerated through the separation region. A magnetic field is applied in a direction perpendicular to travel of the ionized particles through the separation region causing the trajectory of the ionized particles to bend. The mass spectrometer is formed using micromachined techniques and is carried on a single substrate.

Abstract: An analyzer measures properties of multiple chemical samples, and includes an optical filter element having a long axis and positioned at a location where simultaneous multiple light beams, corresponding to the chemical samples to be measured, form a diffuse light spot elongated along an axis which is substantially aligned with the filter element long axis. The analyzer also includes a light source, filter means incorporating the filter element for transmitting spectrally selected portions of the light beams, sample cell means for exposing each sample to its associated light beam, and detector means for detecting the light beams after modification by the samples and after transmission by the filter. In a preferred embodiment, optical fibers carry the light beams to and from the chemical samples.

Abstract: An apparatus and method for measuring potentiometric electrode impedance for diagnostic purpose while continuously reading the results of the process value. A square wave is applied to an external circuit, which in turn is coupled to an electrode assembly output through a capacitor. The output of the electrode is converted into a pulse width modulated signal and sampled. These sampled values are used to calculate the impedance and process output value.

Abstract: A syringe of relatively simple construction which is capable of both accurate and reproducible sample volume withdrawals, including volumes of 1.0 .mu.l or less, is provided. The syringe drive mechanism is preferably adapted for use in a liquid sampling apparatus and includes a threaded lead screw, a drive for rotating the screw, and a syringe having a plunger for withdrawing a liquid sample. The plunger is mechanically connected to the rotating lead screw by a nut threaded onto the screw and a slider mechanism associated with the nut which also is secured to the plunger. The nut is designed so that lateral misalignment of the drive screw does not affect the precise linear movement of the slider mechanism, and consequently, the plunger. This provides a mechanism which is less expensive to assemble and align properly, but which has a high degree of accuracy and reproducibility.

Abstract: A combustible gas sensor includes a housing defining an interior containing a reference bead and a measurement bead which are fully exposed by the removal of the shroud or can therefrom. The beads are electrically connected in series and the reference bead is connected in parallel with a resister to define one side of a Wheatstone bridge. A liner consisting of a disk defining an inner face and an outer face overlies the reference and measurement beads. The inner face of the disk is provided with a slot opening at the inner face which is dimensioned to receive the reference and measurement beads therein. The slot provides a confined space for fluid communication between the fully exposed beads. A through running opening is disposed in the disk on each side of the slot adjacent the end of the slot in which the reference bead is disposed. A channel extends from each of the openings and communicates with the slot.

Abstract: A gas analyzer arrangement for detecting the presence or quantity of a gas of interest includes a source of electromagnetic radiation for directing a light beam through a light conditioning device such that the light beam is collimated into a parallel beam of light. The conditioned light beam is then directed through a gas sample cell which contains a sample of the gas of interest. The gas of interest has associated therewith, vibrational rotational absorption lines specific to that gas and which are effective for altering the light beam according to the absorption characteristics thereof. The altered light beam is then directed to a birefringent etalon device which has been sized specifically to match those absorption lines of the gas of interest.