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8203764 
Journal Article 
Fluorimetric analysis - 1. A study on fluorescent indicators for measuring near neutral ("Physiological") pH-values 
Wolfbeis, OS; Fã¼Rlinger, E; Kroneis, H; Marsoner, H 
1983 
0 
Fresenius' Zeitschrift für Analytische Chemie
ISSN: 0016-1152 
Springer-Verlag 
314 
2 
119-124 
English 
The desired properties of fluorescence pH-indicators are shortly summarised. Fluorescence maxima and pKa values of 28 potential indicators are presented in detail, whilst other data (fluorescence quantum yields, solubility and stability) are given qualitatively. Indicators are divided into groups A and B. Group A compounds exhibit their most long-wave absorption and most intense fluorescence in acidic solution. Group B indicators exhibit their most long-wave absorption and most intense fluorescence in basic solution. Amongst the indicators investigated, some coumarins and HPTS(1-hydroxy-pyrene-3,6,8-trisulfonate) are considered to be the most suitable ones for both acid-base titrations and precise pH-measurements. The HPTS absorption, excitation and fluorescence spectra, decay times, pKa-values, and fluorescence properties as a function of pH and excitation wavelength are given. As a result of its stability, water solubility, long-wave excitation maximum and large Stokes' shift HPTS appears to be the pH-indicator of choice. © 1983 Springer-Verlag.