Abstract: An automatic sampling apparatus particularly adapted for flameless atomic absorption spectrometers has a turntable carrying a ring of sample containers. The turntable is rotatably mounted on a base plate which in turn is mounted for limited pivotal movement on a support. A rinse station for a sample probe is provided on the base plate adjacent the periphery of the turntable. A sample probe in the form of an elongated tube angled at one end to form a pipette-like tip is mounted for swinging movement about a transverse axis and concomitant rotation about its longitudinal axis so that, at both limits of movement about the transverse axis, the probe tip is directed generally downwardly.

Abstract: An a.c. to d.c. converter is disclosed which includes two resetable integrators each for sampling an alternate half-wave of the a.c. voltage to be converted. During each alternate half-wave, when a given integrator is not integrating the input signal, the integrator output is sampled by an analog memory circuit. After the sampling has taken place, the integrator which has been sampled is reset so that it can again operate properly during the succeeding half-wave. The difference of the output for both analog memory circuits is formed so that the d.c. component of the incoming a.c. signal is removed and the remaining residual ripple in the output results only from changes in amplitude of the a.c. signal itself from one-half wave to the next.

Abstract: The present invention is directed to apparatus for flameless atomization of a sample for atomic absorption analysis, which includes a sample tube of electrically conductive material having a transverse bore offset axially towards one end of the tube with respect to the transverse central plane, an electrode arrangement including portions in electrical contact with the sample tube at spaced locations for passing an electrical current through the tube to cause heating thereof, and a system for generating an inert gas flow inwardly from the opposite end of the sample tube and outwardly through the transverse bore.

Abstract: Heat is applied to atomize the residual liquid from a sample transfer probe on which at least the tip is fabricated of heat resistant material. In one embodiment, the sample transfer probe is disposed within an atomic absorbtion spectrometer having a hollow graphite furnace that includes a port through which the sample is dispensed for atomization in the furnace. The probe tip in this embodiment is configured to extend into the graphite furnace while making thermal contact therewith so that the sample residue on the probe tip is atomized simultaneously with the sample in the furnace. Inert gas is connected to the sample transfer probe through a control valve to flush the atomized sample residue from within the probe tip in still another embodiment.

Abstract: An improved graphite tube for use in a flameless atomic absorption spectrometer, which is characterized by a mechanically roughened area on at least a portion of the outer peripheral surface of the graphite tube for providing substantially constant emissivity for pyrometric temperature measurement, and in a preferred form the mechanically roughened area has superimposed thereon a microscopic chemically roughened area.

Abstract: A device for automatically supplying liquid samples to analytical instuments having a support member; a sample source mounted on the support member; a calibration vessel holder mounted on the support member for carrying a plurality of vessels containing neutral or calibration solutions, said holder being movable in a stepwise manner; an intake tube mounted for vertical reciprocating motion corresponding to predetermined points of an operating cycle; and wherein the support member is movable to a first position wherein the sample source is disposed adjacent the intake tube and to a second position wherein one of the vessels in the vessel holder is disposed adjacent the intake tube.

Abstract: Automatic sample preparation method and apparatus for making successive measurements with an analyzer by picking up with a single stepwise movable metering probe, in a first measuring cycle, a sample for measurement from a sample container and a small volume of air; introducing this sample and the air into the inlet of the analyzer; picking up with the same metering probe, in a secondary measuring cycle, a sample for measurement from the same sample container and a small volume of air, and picking up with said metering probe a metered quantity of liquid additive and a second small volume of air; and thence introducing said sample, said liquid additive and said air picked up in the secondary measuring cycle into the inlet of the analyzer.

Abstract: There is disclosed a circuit which supplements a bridge-type detector circuit in order to minimize non-linearities resulting in measurements of thermal conductivity by such type bridges. An auxiliary voltage source is described which has an adjustable output voltage which is servoed to follow the output voltage of a differential amplifier which is connected to the output of the bridge. When the bridge is balanced at the desired operating temperature, the auxiliary supply is switched in and this voltage now controls the current supplied to the bridge instead of the differential amplifier output voltage thus eliminating the cause of the non-linearities at the point of measurement.

Abstract: Method and apparatus for introducing a sample to be analyzed through an introduction aperture into a graphite tube of a graphite tube cell of an atomic absorption spectrometer, wherein a plurality of sample containers containing the samples to be analyzed are placed in a row in a sample holding device, the sample containers being open at both ends. The sample containers are successively transported to an introduction device and a sample container is inserted into the introduction aperture of the graphite tube by means of the introduction device. The sample is transferred from the sample container into the graphite tube and the sample container is removed therefrom and the next subsequent sample container is transported to the introduction device.

Abstract: An automatic sample preparation device for use in flameless atomic absorption spectroscopy or the like, wherein samples to be examined for a particular element are successively mixed with graduated, metered additions of the element to be determined, which includes, in combination, controlled delivery pumping apparatus, a storage vessel system containing dilution agents connected to the inlet side of the pumping apparatus, a dosing probe connected to the outlet side of the pumping apparatus, a stepwise movable carrier, a plurality of sample containers mounted on the carrier, a sample withdrawing device for withdrawing samples from the carrier, and a control unit for moving the dosing probe with respect to the carrier so that one group of at least two successive sample containers on the carrier can be simultaneously mixed with graduated, metered additions of the element to be determined prior to sample withdrawal.

Abstract: A graphite furnace for flameless atomic absorption spectroscopy comprising a graphite sample tube with a sample port at the mid-point of its length. Electrodes supportively contact the tube ends and pass electrical heating current through the tube. The electrodes have hollow cylindrical portions which laterally envelope the tube over substantially its entire length, one of the electrodes being longer than the other and containing a radial bore in registration with the sample port. The cylindrical portions of the electrodes are disposed with complementary-shaped recesses in cooling jackets which encase all but the mid-length regions of the electrode cylindrical portions. The electrodes fit readily in the cooling jackets at room temperature due to differential expansion of these members. The sample tube, electrodes, cooling jackets and associated structure are mounted on a base with provisions for adjustment of the tube about various orthogonal axes.

Abstract: A method of atomization of a sample for analysis by atomic absorption spectroscopy in which the sample is progressively heated to drying, ashing and atomization temperatures by subjecting it sequentially to discrete ambient temperature increments.A preferred form of apparatus for carrying out the method takes the form of a graphite fabric conveyor belt which carries the sample substance and travels transversely through three hollow cylindrical graphite tubes disposed in spaced justaposition with longitudinal axes parallel. The belt passes through each tube in sequence, by way of pairs of aligned longitudinal slots in the sidewalls of the tubes, the slots defining a common chordal plane of the tubes. Each tube is maintained, respectively in the direction of belt travel, at drying, ashing and atomization temperature for the particular sample. The tubes are heated by an electrical current of appropriate magnitude passed between pairs of electrodes associated with the ends of the tubes.

Abstract: A heated graphite sample-atomizer for flameless atomic absorption spectroscopy in which a graphite sample tube is coaxially disposed within a pair of generally cylindrical electrode members which jointly envelope substantially the entire tube and define therewith a cylindrical flow passage for inert gas. The electrode members make electrical contact with respective ends of the tube to enable passage of a heating current therethrough. At least the outer end portions of the electrode members are telescoped within respective cooling jackets, the external cylindrical surfaces of the electrode members making a snug fit with complementary internal cylindrical surfaces of the cooling jackets at room temperature. The respective thermal expansion coefficients of the materials of the electrode members and cooling jackets are such as to create a press fit between the electrode members and cooling jackets under operating conditions.

Abstract: A integrator circuit is calibrated prior to measuring input signals therewith, by applying a reference voltage thereto with the output thereof applied to a comparator which has an output threshold set by a limit value signal proportional to the reference voltage. Clock pulses are accumulated by a counter until the comparator output threshold is reached and then a synchronizing means is actuated to simultaneously disconnect the reference voltage from the integrator and stop the counter, to reset the integrator, and to simultaneously connect the input signal to the integrator and the clock pulses to count down the accumulated count in the counter which thereby initiates the measuring mode. When the counter reaches zero, an output signal is produced which disconnects the input signal from the integrator to thereby stop the measuring mode.

Abstract: In a connecting device for connecting chromatographic separating columns of glass to terminal fittings on a chromatographic apparatus, each end of the column is surrounded by a metallic sleeve. A sleeve made of synthetic plastic material, which is of substantially stable shape at least up to a temperature of 350.degree. centigrade even if subjected to pressure, is interposed between said end and said metallic sleeve. A preferred material is polyimide. The plastic sleeve has at least one conical end face and is held in sealing engagement with the end of the separating column, on one hand, and with the metallic sleeve, on the other hand, by a sleeve shaped thrust member, which is axially movable relative to the metallic sleeve to exert an axial force on said plastic sleeve. A radial sealing force is exerted on the snthetic plastic sleeve through its conical end face by an abutting complementary conical surface.

Abstract: Operation between a beam switch which directs light to a photoelectric detector and a gating means for directing signals from the photoelectric detector to separate storage channels is synchronized by generating a marker pulse within a sequence of clock pulses which correspond to the positions of the beam switch. Signals from the separate storage channels are directed to an analyzing means in a predetermined sequence by the gating means and sequencing within the analyzing means is also accomplished thereby. Furthermore, comparative analysis between signals corresponding with two positions of the beam switch is provided at the input to and/or the output from the separate storage channels.