Substance of an optical fluorescence measuring arrangement for measuring the pH of a sample and optical sensor with such an indicator substance
US5308581A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 31, 1992 |
| Grant date | May 3, 1994 |
| Priority date | — |
| Expiry date | Jul 31, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/6445
- WIPO fieldMeasurement
- WIPO sectorInstruments
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.dp of the acid in the excited state (S.sub.1, X) of the indicator is higher than the decay rate k.sub.A of the excited state.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.