Specrrochimrca Acu, Vol. 438. No 2, pp. V-VI, 1988. Printed in Great Bnmn

058~8547188 S3.M) + 0 00 0 1988 Per@mon JoumalsLtd

NEW PATENTS

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4681530

GAS CONTROL DEVICE FOR CONTROLLING THE FUEL GAS

AND OXIDIZING AGENT SUPPLY TO A BURNER IN AN ATOMIC

GORGON SPECTROMETER

Bernhard Huber, Uberlingen, Federal Republic Of Germany assigned to The Perkin-Elmer Cor- poration

The present invention is directed to a gas control device for controlling the fuel gas and the ox- idizing agent supplied to a burner in an atomic absorption spectrometer. The device includes a pressure controller and a downstream flow- meter, connected to the aforesaid pressure con- troller in each of the devicef 3 s supply conduits to an atomizer, oxidizing agent port and full gas port of the burner. Each flowmeter employed in the preferred embodiment of the invention is comprised of a turbine wheel which is exposed to the gas flowing through the flowmeter. By the rotation of the turbine wheel output, signals are generated depending on the angular rate thereof and thus as a function of the gas flow rate. These output signals are input into a control unit and a set of servomotors, each associated with one of said pressure controllers, are reproducibly ad- justed under the control of said control unit, even under unstable pressure conditions, to selected gas flow rates. + RE

4684251

SPECTROMETER

Geert Brouwer, Sipke Wadman, Waalre, Netherlands assigned to U S Philips Corpora- tion

A spectrometer includign a flame atomiser (7) is provided with a sample diluter comprising a mix- ing vessel (1) having a diluent supply channel (20) and a sample supply tube (10). The mixing vessel (1) has a converging lower portion (2) to which a outlet tube (5) is connected, the outlet tube feeding a mixture of sample and diluent to a nebuliser (47). The sample supply tube (IO) is aligned with and spaced from the outlet tube (5). Sample liquid from the sample supply tube (10) passes into the outlet tube (5) as a central core (29) entrained in a sheath of diluent. The sample and diluent flow through the tube (5) with a laminar flow due to the profile of the mixing ves- sel (1) thus preventing the sample liquid from coming into contact with the wall of the outlet tube (5). Consequently memory effects are reduced. The rate of flow of sample may be con- trolled automatically by means of a processing and control circuit (40) which has an output (B) which controls the speed of a stepping motor (61) which is arranged to advance a plunger (13) in a syringe (15) containing the sample liquid. The processing and control circuit calculates the abs- orption or emission of the sample in the atomiser (7) and controls the stepping motor (61) to bring the calculated value within the most sensitive range of the instrument.