Radiant energy – Luminophor irradiation
Patent
1981-02-09
1984-01-24
Howell, Janice A.
Radiant energy
Luminophor irradiation
250308, 2504591, G01N 2300, G21K 500
Patent
active
044278926
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the detection and determination of species by fluorescence measurements, including detection and determination of both fluorescent species and species which cause quenching of fluorescence, and in particular to detection and determination of these species in flowing liquid systems such as liquid chromatography systems.
Liquid chromatography techniques are very widely used for separation and determination of chemical compounds contained in mixtures, and amongst the various detectors which are used to detect compounds of interest after separation, fluorescence detectors are particularly preferred in view of their high degree of sensitivity. Currently available fluorimetric detectors use visible radiation to bring about excitation of the fluorescent species which gives rise to problems of instability. A mercury line or Xenon arc lamp is usually used for exciting fluorescence but both are susceptible to variations in intensity, so that expensive power supplies or other electronic systems must be used to compensate for radiation intensity fluctuation. Furthermore, since the emitted fluorescent radiation must be detected at right angles to the incident exciting radiation, a substantial proportion of the total fluorescence is generally lost. Moreover, the use of filters and monochromators to reduce interference results in a further reduction in the proportion of the total fluorescent radiation which can be detected.
A new and improved form of fluorimetric detector has now been devised, particularly for use in liquid chromatography systems, which does not suffer from the instability of prior art visible radiation excitation fluorimetric detectors, and moreover advantageously permits detection of a greater proportion of the total fluorescence produced than prior fluorimetric detectors.
According to the present invention a fluorimetric detector comprises a radionuclide as the fluorescence excitation source.
The invention also includes a method for the detection or determination of a species by fluorescence measurements, in which liquid comprising the species to be determined is exposed to fluorescence exciting radiation from a radionuclide source and fluorescence thereby produced is monitored and compared with the fluorescence of the same liquid in the absence of the species.
The detector and method of the invention are widely applicable to the detection and determination in liquids of fluorescent species and species which cause quenching of fluorescence, generally in flowing liquid systems. For instance, the invention may be applied to the monitoring of such species in effluent, liquid product, e.g. petrochemical product, or other streams. In particular, however, the invention is applicable to fluorescence detection in liquid chromatography systems, especially high performance liquid chromatography (HPLC) systems.
The species which may be detected and determined by the present invention may be any species which are fluorescent in response, either directly or indirectly, to radionuclide radiation or cause quenching of such fluorescence, and may include any of those species which may be determined by conventional fluorescence techniques which use visible radiation to excite fluorescence. Such species include fluorescent species such as unsaturated hydrocarbons, e.g. those unsaturated hydrocarbons which may be present in a petrochemical product stream. Such species may also include species which quench fluorescence such as halogen substituted hydrocarbons, thionyl compounds and aldehydes. Generally, however, the invention may be used to detect or determine specific species such as drugs, aromatic compounds and polycyclic hydrocarbons, which it may be desired to detect in liquid chromatography systems. For example, fluorescent species which may be detected using the method and apparatus of the invention include: p-terphenyl, anthracene, fluorene, 1,6-diphenyl-1,3,5-hexatriene, 1,4-di(2-methylstyryl)benzene, biphenyl, tetraphenylbutadiene naphthalene, phenanthrene, acenaphthene, anisole, indene
REFERENCES:
patent: 3751661 (1973-08-01), Packer et al.
patent: 4125769 (1978-11-01), Marten et al.
Jordan et al., Specialia 15.3.1969, pp. 335-336.
Gifford Lawrence A.
Malcolme-Lawes David J.
Howell Janice A.
National Research Development Corporation
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