Sprcfmhimica Acta, Vol. 41B, No. 8, pp. 14, 1986. Printed in Great Britain.

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NEW PATENTS

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4557603

DETECTION MEANS FOR THE SELECTIVE DETECTION OF GASES, BASED ON OPTICAL

SPECTROSCOPY

Oskar Oehler, Alexis Fries, Zswitzerlana

An optical detection system for selectively detec- ting gases comprises a light source emitting light thermally or mechanically modulated and sup- plied to a measuring cell. The light source in- cludes an emitter enclosed in an ellipsoid reflector. The ellipsoid reflector can receive measuring gas directly, or is evacuated or filled with an inert gas which does not absorb in the measuring gas absorption range. With measuring gas supplied directly to the reflector, the light emanating from the reflector is supplied to a wide-band detector, combined with a mono- chromator, e.g. an optical narrow-band filter. With an evacuated or inert gas filled reflector, af- ter traversing a monochromator, the light is irradiated into a photoacoustic detection cell containing the measuring gas. The photo- acoustic cell is completely or approximately closed during measurement. Devices, providing the acoustic decoupling in the photoacoustic cell during the measurement and gas exchanges, can include capillaries in the cell wall, liquid cutout devices, mechanical valves or diaphragm pump- valve combinations. Microphone signals pro- cessed by a lock-in amplifier operating in a digital off-line manner and controlled by a microprocessor can control the system. The gas scavenging and signal processing of several gas detector units can take place with a single pro- cessor unit,

4565447

PHOTOMETRIC APPARATUS WITH MULTI-WAVELENGTH

EXCITATION

Kenneth E Nelson assigned to Millipore Cor- poration

A system for photometric measurement of op- tical properties of a fluid medium utilizing multi- wavelength excitation includes a movable diffraction grating that is continuously oscillated over the spectral range of interest and a flash- lamp producing high intensity, short duration flashes. The angular position of the grating at the time of a flash determines what wavelength of optical energy will be passed to the remainder of the system. Because the flash duration is brief in relation to the period of movement of the grating, the flash effectively freezes the motion of the grating allowing the high intensity output of the flashlamp to be supplied to the fluid medium, while successive flashes permit measurement at many different wavelengths in near simul- taneous fashion. The system is disclosed for use in an absorbance detector for liquid chromatography.

4565790

METHOD FOR FLUORESCENCE SPECTROSCOPIC

DETERMINATION OF A BIOLOGICALLY ACTIVE

SUBSTANCE

Ilkk Hemmila, Salifu Dakubu, Turku, Finland assigned to WALLAC Oy