Chemistry: electrical and wave energy – Apparatus – Electrolytic
Patent
1990-09-25
1992-06-02
Niebling, John
Chemistry: electrical and wave energy
Apparatus
Electrolytic
204416, 204418, G01N 2726
Patent
active
051184052
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method for pH measurement with a luminescent probe, a new luminescent probe complex for measuring pH, a luminescent probe membrane, a device for measuring pH and a method for measuring pH using the device.
BACKGROUND ART
Heretofore, devices have been known that use an electrode for measuring pH comprising a glass electrode and a reference electrode. Devices have also been known which use pigments for measuring pH. However, a pH measuring technique using a luminescent complex and a probe incorporating the complex have not been known in the art.
With the conventional pH measuring techniques, it is difficult to measure proton concentrations in a micro environment such as within a membrane. A technique of measuring pH locally, on a molecular scale has been long sought after in the art.
Therefore, it is an object of the present invention to provide a new luminescent probe complex for measuring pH which enables the measurement of pH easily in local areas, a luminescent probe membrane, a device for measuring pH and a method for measuring pH using the device.
DISCLOSURE OF INVENTION
The present invention relates to a luminescent probe complex for measuring pH comprising a polypyridine ligand having ion dissociable substituents in its carbon ring and transition metal ions selected from the elements of group VIII of the periodic table.
The present invention further relates to an luminescent probe membrane for measuring pH in which the above luminescent probe complex is contained in a macromolecular membrane.
The present invention further relates to a device for measuring pH in which the above luminescent probe membrane is immobilized at the tip of an optical fiber.
The present invention further relates to a method for measuring pH in which the luminescence intensity of the excited state of the above luminescent probe complex is measured.
The present invention will now be further explained in detail.
The luminescent probe complexes according to the present invention are complexes comprising polypyridine ligands having carboxyl, sulfate, hydroxy, ammonium or pyridinium groups etc. as ion-dissociable substituents on their respective carbon rings and a transition metal ion selected from the elements of group VIII of the periodic table.
The above polypyridine ligands include 4,4'-dicarboxy-2,2'-bipyridine-4,4'-disulfonic acid-2,2'-bipyridine, vasophenanthroline disulfonic acid, etc.
The transition metal ions include ions such as ruthenium, iridium, osmium, iron, rhodium ions.
The complexes used in the luminescent probe include tris (4,4'-dicarboxy-2,2'-bipyridine) ruthenium (II) complex (hereinafter referred to as "Ru(DCbpy).sub.3.sup.2+, tris (4,4'-disulfonic acid-2,2'-bipyridine) ruthenium (II) complex, tris (vasophenanthroline disulfonic acid) ruthenium (II) complex, tris (4,4'-dicarboxy-2,2'-bipyridine) iridium (II) complex, tris (vasophenanthroline disulfonic acid) Fe (II) complex etc.
These luminescent probe complexes of the present invention luminesce from the excited state (mainly the triplet state) when the complexes, in solution or immobilized in a membrane, are irradiated with light having the maximum absorbance wavelength (.lambda. max) or a wavelength near .lambda. max. The present inventors have discovered that the luminescence intensity of the complexes of the present invention depends on the proton concentration in a system in which they are contained. This pH dependency of the luminescence intensity is based on the fact that dissocation of a substituent on the ligand depends on the proton concentration. The dissociation of the substituents depending on the proton concentration changes the charge state of the complex, which brings about a change in the luminescence intensity. The luminescence intensity of the complex is therefore dependent on the pH.
The luminescent probe complex does not influence the pH of the solution to be examined when dispersed in the solution. The complex is therefore suitable for being used to measure pH in solution. The co
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patent: 4293310 (1981-10-01), Weber
patent: 4582589 (1986-04-01), Ushizawa et al.
patent: 4708494 (1987-11-01), Kleinerman
patent: 4874736 (1989-10-01), Drent
patent: 4892640 (1990-01-01), Wolfbeis et al.
Analytical Chemistry, vol. 54, No. 4, Apr., 1982, "pH Sensor Based on Immobilized Fluoresceinamine" by Linda A. Saari, et al., pp. 821-823.
Asakura Tetsuo
Kaneko Masao
Nakamura Hideki
Shimomura Takeshi
Sugise Hiroshi
Bell Bruce
Niebling John
Rikagaku Kenkyusho
Terumo Kabushiki Kaisha
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