Related Experiment Video
Updated: Feb 9, 2026

Nanostructured Ag-zeolite Composites as Luminescence-based Humidity Sensors
Published on: November 15, 2016
A luminescent europium complex for wide-range pH sensors and sensor microtiterplates
Wafaa Waleed Al-Qaysi1, Axel Duerkop1
1Institute of Analytical Chemistry, Chemo and Biosensors, University of Regensburg, 93040 Regensburg, Germany. axel.duerkop@ur.de wafaa.al-qaysi@chemie.uni-regensburg.de.
Abstract:
In this work, we show a new concept of a luminescent wide-range pH indicator based on a europium complex and its implementation in sensors and sensor microtiterplates. For this purpose, we complexed europium with the ligands gallic acid (Gall) and pyridine dicarboxylic acid (PDA) that carry groups with wide ranging pKa values and the antenna ligand theonyl trifluoroacetone (TTA). This yields an indicator that overcomes the typical drawbacks of many optical pH indicator dyes which mostly cover three pH units, only. The spectral characterization of the new europium complex Eu3+-TTA-Gall-PDA in a molar ratio of 1 : 3 : 1 : 1 in aqueous buffer delivers a luminescence emission that is dependent on pH over up to 8 orders of magnitude from pH 2-10 in aqueous solution. It was therefore embedded into sensor membranes made of cellulose acetate (CA) which respond reversibly from pH 2-7 over 5 orders of magnitude within several minutes. Moreover, the first high-throughput pH sensor microtiterplate based on this indicator showed a dynamic range from pH 2-8 over 6 orders of magnitude and is suitable for up to 24 h of continuous use.
Related Concept Videos
Range
15.9; 16.1; 15.2; 14.8; 15.8; 15.9; 16.0; 15.5
Measurements of the amount of soda in a 16-ounce can vary since different subjects record these measurements or since the exact amount - 16 ounces of liquid, was not...
¹H NMR: Long-Range Coupling
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene...
Variation: Normal Distribution, Range, and Standard Deviation
Angle of Twist - Elastic Range
Range Rule of Thumb to Interpret Standard Deviation
For instance, the range rule of thumb can be used to find the tallest and the shortest student in a class, given the mean student height and standard deviation. If the mean student height is 1.6 m and the standard deviation, s is 0.05 m, the height...
Protein Complex Assembly
Many viruses self-assemble into a fully functional unit using the infected host cell to...

