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Microtiterplate phosphate assay based on luminescence quenching of a terbium complex amenable to decay time detection |
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| Authors: | Matejka Turel Axel Duerkop Alla Yegorova Yulia Scripinets |
| Institution: | a Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, Universitaetsstrasse 31, 93040 Regensburg, Germany b Faculty of Mechanical Engineering, Centre of Sensor Technology, University of Maribor, Smetanova ulica 17, 2000 Maribor, Slovenia c A.V. Bogatsky Physico-chemical Institute, National Academy of Sciences of Ukraine, 86 Lustdorfskaya doroga, 65080 Odessa, Ukraine |
| Abstract: | We describe a terbium-ligand complex (TbL) for a microtiterplate assay for phosphate (P) in the 0.3-100 μmol L−1 range based on luminescence quenching. As the pH optimum is at neutral pH (7.4) the probe is quenched by both, primary (H2PO4−) and secondary phosphate (HPO42−). The LOD is 110 nmol L−1. A Stern-Volmer study revealed that quenching is mostly static. Due to the ms-decay time of TbL, the first luminescence lifetime assay for phosphate could also be developed. The lifetime-based calibration plot is linear between 0.5 and 5 μmol L−1 of P. The effect of various surfactants on assay performance and a study on interferents are presented. The probe was successfully applied to determination of P in commercial plant fertilizers and validated against the molybdenum blue test. The probe is the most sensitive lanthanide-based probe for phosphate. |
| Keywords: | Fluorescent probe Lanthanide luminescence Phosphate Time-resolved spectroscopy Microtiterplate assay Lifetime assay |
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