Abstract: Electrical contact members 20, 22 for supplying transverse electrical current to a tubular furnace member (22) for electrothermal atomization of samples for analysis by atomic absorption spectrophotometry, the tubular furnace member having diametrically opposite, longitudinally-extending contact ribs (84, 86). The contact members (20, 22) form, in operative assembly, a cavity 88 in which tubular furnace member (24) is accommodated and is held between V-shaped channels (44, 76) in contact members (20, 22). Cavity 88 is formed by a recess (36) in one contact member (20) and covered, except for a separating gap, by the other contact member (22). Respective inert protective gas passages (62, 82) terminate at one end in channels 44, 76.

Abstract: A pocket instrument for sampling breath air in situ, includes a microprocessor-controlled directional control valve with needles at an outlet to which needle the sample vessels are attached. The directional control valve is arranged to be connected through another outlet to the atmosphere and to a collecting chamber respectively, which collecting chamber is provided with a feeding device for accommodating and delivering the breath air.

Abstract: The basic concept of this invention involves the use of a wire or capillary tube as a template strand. The outside diameter and shape of the template strand correspond to the inside diameter and shape of a desired separation capillary. A detector may be incorporated by providing a pair of electrode wires, or the ends of a pair of optical fibers, and pressing them against opposite sides of the template. As plastic is then polymerized around this asssembly by casting or molding. The template is then removed, leaving a capillary channel with a sidewall incorporating the wire electrodes and optical fibers. Using this method, it is possible to form a single unit including a separation capillary, conductivity detector, and spectroscopy detector.

Abstract: A thermal conductivity cell is described whose elements are well protected against short term temperature fluctuations, changes in flow rates, leaks, and vapor pressures of construction materials. The sample and reference chambers are formed within a relatively large copper block with a controlled thermal time constant. The thermal elements are isolated from the gas flow paths by porous metal plugs which are thermally "clamped" to the block. Element feed-throughs are potted in thermally conductive epoxy to minimize the effect of temperature gradients.

Abstract: An atomic spectrometer in combination with an atomizer apparatus for atomizing a test sample into an atomic state for analysis in the atomic spectrometer. The atomizer apparatus includes a heater for heating a sample to free individual atoms of the sample for atomic spectroscopy, a tube member containing a packing of an adsorbent, a reagent adsorbed on the adsorbent which reacts with a metal constituent in a sample to form a metal complex which adsorbs to the adsorbent at a first temperature and is volatile at a second higher temperature for desorption from the adsorbent, and a heater for heating the tube member.

Abstract: The advantage of sustained wavelength accuracy and mechanical simplicity of a spectrophotometer using a photodiode array as photometric detector and a fixed diffraction grating as dispersion means may be limited to a relatively short wavelength range by problems of stray light, second order errors and overloading of the detector at portions of the wavelength range. By utilizing repeat scanning of the array, each scan being modified by using a different source lamp and correction filters, freedom from the cited problems over part of each scanned wavelength range can be effected. A computer controls the scan sequence and combines the usable portion of each scan to produce error free operation over an extended range.

Abstract: In a polychromator, the image plane or the focus line (28) is adapted optimumly to the plane of a detector (26), e.g. to a diode-array. At the same time, an optimum linear wavelength scale is obtained on the detector (26). To this end, an arrangement having a concave grating (14), and an imaging mirror (20) is provided. An optimizing method is described by which both curves can be optimized in converging steps by alternate variation of the distance b between concave grating (14) and mirror (20) and the asymmetry measure G' of the concave grating (14).

Abstract: A method for calibrating a monochromator to compensate for mechanical imperfections in its diffraction grating and grating drive assembly employs a two stage interactive procedure which permits the use of small (0.2 nm) spectral regions for the identification of emission lines. An iterative, self-consistent, discrete Fourier transform is used for the determination of multiple positioning correction terms. When the Fourier calculations are completed, the results of the calibration procedure are presented by the system to the analyst for acceptance. If accepted, the positioning error of the primary calibration line is measured, stored and used by the system to maintain a zero centered distribution of positioning errors each time the monochromator is reinitialized.

Abstract: A gas conducting tube (12) with a flat end (14) cut off at an angle is pivotal above the burner head 10 for lighting the flame of an atomic absorption spectrometer. Gas emerging from the burner is passed through the tube from the first end 14 to a second end 16 where a glow filament 24 is arranged. The diverted gas is lit and flashes back to the burner, whereby the flame thereof is lit. After the flame has been lit, the tube 12 is rotated out of the area of the burner head 10.

Abstract: A burner assembly for an atomic absorption spectrometer having carrier (20) fixed to the burner head (14) and mounting a flame sensor (96) and an ignition device (16) so as to permit a single alignment of the flame sensor (18) and the ignition device (16) relative to the burner head (14) and subsequent movement or adjustment of the burner relative to the housing without changing the mutual positions of the ignition device (16) and the flame sensor (18) and while the flame is burning.

Abstract: An apparatus and method for determining the zero line in atomic absorption spectrometers having an atomizer and a burner for atomizing the sample wherein the flow of oxidizing agent supplied to the atomizer is interrupted by means of a switching valve and an additional flow of oxidizing agent is supplied to the burner through a by-pass conduit by-passing the atomizer with the additional flow being equal to the flow of oxidizing agent to the atomizer during operation of the atomizer and the absorption of the measuring light beam defining the zero line.

Abstract: A closure and method of assembly for sample vials comprising a cap and a septum with the septum having a plurality of radially extending protrusions for retentive engagement with the cap to retain the septum and annular disk within the cap during positioning of the closure on the sample vial.

Abstract: The invention resides in the temperature control of the oven of a gas chromatograph. A variable speed fan circulates air within the oven. Vents in the oven wall open automatically in response to pressure imbalances between the ambient atmosphere and the oven interior. Temperature is controlled by regulated exchanges of ambient and oven air produced by variations in fan speed.

Abstract: In a sensitive analytical instrument having an optical bench carried by a base member, new and improved vibration and shock isolation apparatus which includes three spaced pneumatic mounts interposed between the optical bench and the base member to provide vibration and shock isolation therebetween, each of the mounts having a preselected optimum linear range of operation, a source of pressurized gas, apparatus for individually controlling the inflation and deflation of each of the mounts with pressurized gas to maintain actual operation of each of the mounts within its preselected optimum linear operating range.

Abstract: An improved power supply system of smaller size and lower cost than prior art supplies is described for starting and maintaining the running of a deuterium arc lamp at a constant current level; by use of switching circuitry with solid-state components the necessity of transformers, relays and timing circuits has been obviated with a resultant major reduction in size, cost and cooling requirements of the supply; an improved starting sequence lengthens lamp cathode life.

Abstract: A spectrophotometer includes means for ensuring that the active area of a detector is always filled regardless of the resolution aperture setting of the instrument.

Abstract: Inert gas is supplied to a closed reagent reservoir for reagent dosing in producing gaseous measuring samples according to the "hydride method". Thereby, reagent is pressed into a sample vessel through a reagent dosing conduit. A manometric switch is provided at the inert gas connecting conduit to produce a defined reagent flow, by means of which manometric switch a valve located in the connecting conduit is driven into its closed position, if a preset pressure has been reached.

Abstract: There are disclosed gas chromatographic ionization detectors of the argon and electron capture types. The free electrons required for the functioning of the detectors is achieved by irradiating a solid photoemissive element with ultraviolet radiation.

Abstract: The circuit includes an inverter to be connected to a source of d.c. power. The inverter has a transformer with a center-tapped primary winding. Separate controllable switching devices are connected to the respective ends of the primary winding. Both switching devices are arranged to be connected in common to one output terminal of the d.c. power source. The center tap of the transformer primary winding is arranged for connection to the other output terminal of the d.c. power source. The transformer has a laminated silicon steel core, and includes a secondary winding arranged for connection across the input terminals of a gaseous discharge lamp. A control circuit is connected to control conduction by the separate controllable switching devices in alternating sequence at a desired frequency of operation.

Abstract: This invention is directed to a digital wavelength calibration system for a spectrophotometer, which includes a photodiode array that forms an output detector for the spectrophotometer, a light source for generating at least one reference emission line of known peak wavelength, a computer controlled mechanism for causing the peak of said reference line to fall in close proximity to the center of a preselected pixel of said photodiode array, peak location computing apparatus for computing the exact position data of the peak relative to the pixel center in terms of the pixel spacing and the ordinal number of the preselected pixel and for retaining this position data for subsequent wavelength computation, wavelength identification computing apparatus for computing the numerical relationship data of the ordinate number of each pixel to the wavelength falling on that pixel and for retaining this relationship data for subsequent correlation with data generated by the pixel, and apparatus for computational processin