Abstract: A luminescence-optical indicator for determining the activity of alkali metals based on decay time includes at least three components that are chemically bound to one another, i.e., a fluorophor, a functional group with which the luminescence decay time of the fluorophor can be influenced, and a ionophor binding the alkali metal ions to be measured in a selective and reversible manner, the effect of the functional group on the decay time of the fluorophor being altered in dependence on the activity of the alkali metal ions.

Abstract: An indicator for use in a luminescence-optical configuration for continuous and reversible measurement of the pH of a sample within a relevant measuring range (M), whose luminescence decay time .tau. is dependent on the pH of the sample, is characterized by the following properties. The pK.sub.a value of the acidic or basic indicator is in the relevant measuring range when the indicator is in its electronic ground state (S.sub.0). The protonation rate k.sub.p of the base, or deprotonation rate k.sub.dp of the acid in the excited state (S.sub.1, X) of the indicator is lower than the decay rate k.sub.A of the excited state, and the luminescence decay times .tau..sub.S and .tau..sub.B of the acidic forms (AH*, BH.sup.+*) and the basic forms (A.sup.-*, B*) of the indicator are different from each other. If the pK.sub.a .tau. value of the indicator in its electronically excited state (S.sub.1, X) is within the relevant measuring range, the protonation rate k.sub.p of the base, or deprotonation rate k.sub.

Abstract: A method for the quantitative determination of one or more chemical parameters of a sample medium employs a fluorescent agent which is not responsive to the parameter to be determined and which has an excitation spectrum and an emission spectrum, and a closely adjacent chromogenic agent which responds to the parameter of the sample medium to be determined by a change in its absorption spectrum the emission spectrum of the fluorescent agent at least partically overlapping the absorption spectrum of the chromogenic agent. The absorption maximum of chromogenic agent is shifted in accordance with the parameter to be determined, causing a reduction of fluorescence decay time t in the fluorescent agent, thereby enabling quantitative determination of the chemical parameter with improved long-term stability and infrequent calibrations.

Abstract: In order to improve the response behavior of an optical sensor for determining at least one parameter in a liquid or gaseous sample, the sensor including a substrate which is provided with carrier particles and a fluorescent indicator immobilized thereon, the substrate is configured as a polymer film transparent to both excitation and emission radiation, and the individual carrier particles carrying the fluorescent indicator in immobilized form are bonded with only part of their surface to a thin layer of a thermoplastic material adhering to the polymer film and assume thermosetting properties after the carrier particles have been pressed in, whereas the other part of the surface of the carrier particles extend into an optically transparent hydrogel layer which covers the thermoplastic layer and in which the carrier particles are anchored mechanically. Such sensors may easily be attached to the end of an optical waveguide and may be made in any size by a simple punching operation.

Abstract: In order to improve a one-way measuring element, which may be inserted into an analyzer for analyzing gaseous or liquid samples and which comprises a measuring channel with a measuring zone and one or more sensors located therein, the proposal is put forward that the one-way measuring element be provided with a sensor part whose measuring channel has seals on both ends, and with a sample-taking part, and that a coupling element be placed at the inlet end of the measuring channel for direct coupling of the sample-taking part containing the gaseous or liquid sample, and that the measuring channel be filled with a calibrating and storage medium prior to the measuring process, and that the calibrating and storage medium contained in the measuring channel be displaced by the sample flowing in after the sample-taking part has been coupled to the sensor part. The one-way measuring elements obtained in this way are characterized by great simplicity of design and ease of handling.