Optics: measuring and testing – For light transmission or absorption
Patent
1985-10-07
1988-04-26
Laroche, Eugene R.
Optics: measuring and testing
For light transmission or absorption
356 51, 250343, G01N 2100
Patent
active
047400862
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention is in the field of photoacoustic spectroscopy, acoustics, electronics and biosensor technology, and relates to an apparatus for detecting gases, including vapors dissolved in a liquid or mixed as condensate therewith. The gases can come from a biological reaction. The detection of the gases or vapours is based on the photoacoustic effect. An apparatus for detecting the corresponding electric signals is also described.
BACKGROUND OF THE INVENTION
There is without doubt considerable interest in simple apparatus for the reliable, selective detection of gases. Such gases can either be present directly as components of a gaseous mixture, such as air, or from a biological tissue, such as from a photosynthesizing plant leaf, or e.g. from a biological reaction. The biologically active systems can be living organisms, such as bacteria or biologically active extracts from biological samples, e.g. enzymes. The biologically active system is generally suspended in the liquid, namely water, or is immobilized on a carrier, e.g. a plastic, metal or glass surface.
An apparatus for the detection of gases dissolved in a liquid and formed e.g. by a biological reaction are described in Swiss Patent Application 572/84-1 of Feb. 7th 1984.
However, there are also microbiological systems such as enzymes and bacteria, which are reactive with the air. They either can be present in aerosol form, or, as stated, can be immobilized on a carrier.
If a substrate is added, which substrate can be decomposed by the biologically active system, then gaseous products can form. The gas produced is then a measure of the activity of the biological organism or the bioactive extract.
On the basis of the gas production, information can also be obtained on the concentration of the substrate. As in general biological reactions take place in a highly specific, selective manner, the possibility arises of obtaining, on the basis of the determination of the gases produced, clear and qualitative information on the substrates. Equipment operating according to this principle are covered by the term biosensors. The problem arises of detecting the reaction product, i.e. to produce an electric signal, whose quantity is related to the concentration of the dissolved gases.
For the detection of gases, it is possible on the one hand to use chemical methods, such as titration, calorimetry, gravimetric determination of precipitates, etc. and on the other handpurely physical methods, such as optical spectroscopy, mass spectrometry, etc.
Admittedly chemical methods are generally simple with regards to the equipment, but as a result of the complexity of the reaction sequence, e.g. the reagent supply, separation by filtration, etc., they are less suitable for automatically controlled measurements.
It may also be necessary to carefully separate the apparatus where the biological decomposition takes place, the so-called bioreaction from the chemical reactor, in order to prevent poisoning by chemicals of the bioactive, systems.
Another unfavourable point in chemical determinations is the time taken for the chemical reaction and for the test specimen or sample preparation.
Therefore preference is given to physical determination of gaseous biological reaction products. Unfortunately corresponding methods are usually linked with high equipment expenditure, particularly in the case of spectroscopic methods. However, it must be stressed that optical-spectroscopy methods are characterized by high reliability and selectivity, so that further comment will be made thereon.
The following spectral ranges are worthy of consideration for the optical-spectroscopic detection of biological products: ultraviolet and visible range (180-800 nm), and infrared range (0.8 to 20 .mu.m).
In the ultraviolet and visible spectral ranges, the molecules in question generally have broad-band and less specific absorption structures. Thus, apart from exceptions, this spectral range is generally not very important. However, with regards to selective detection
REFERENCES:
patent: 4051372 (1977-09-01), Aine
patent: 4188543 (1980-02-01), Brunsting et al.
patent: 4197369 (1980-04-01), Weaver
patent: 4220715 (1980-09-01), Ahnell
patent: 4557603 (1985-12-01), Oehler et al.
Rosengren, Optimal Optoacoustic Detector Design, Applied Optics, vol. 14, No. 8, Aug. 1975, pp. 1960-1976.
Bults et al., Photoacoustic Measurements of Photosynthetic Activities in Whole Leaves Photochemistry and Gas Exchange, Biochimica et Biophysica Acta (1982), pp. 452-465.
Cahen, Photoacoustic Cell for Reflection and Transition Measurements, Rev. Sci. Instrium, Sep. 1981, vol. 52, No. 9, pp. 1306-1310.
Kunz Heinrich
Kuster Niels
Mosbach Klaus
Oehler Oskar
Seifert Martin
LaRoche Eugene R.
Pascal Robert J.
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