title: Microtiterplate phosphate assay based on luminescence quenching of a terbium complex amenable to decay time detection.
abstract: We describe a terbium-ligand complex (TbL) for a microtiterplate assay for phosphate (P) in the 0.3-100 micromol L(-1) range based on luminescence quenching. As the pH optimum is at neutral pH (7.4) the probe is quenched by both, primary (H(2)PO(4)(-)) and secondary phosphate (HPO(4)(2-)). 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 micromol 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.
authors: Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, Universitaetsstrasse 31, 93040 Regensburg, Germany.
authors: Matejka
authors: M
authors: Turel
authors: Axel
authors: A
authors: Duerkop
authors: Alla
authors: A
authors: Yegorova
authors: Alexander
authors: A
authors: Karasyov
authors: Yulia
authors: Y
authors: Scripinets
authors: Aleksandra
authors: A
authors: Lobnik
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry*; D005308:Fertilizers / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008163:Luminescent Measurements / Q000379:methods*; D010710:Phosphates / Q000032:analysis*; D013501:Surface-Active Agents / Q000737:chemistry; D013725:Terbium / Q000737:chemistry*; D013997:Time Factors
chemical_list: D056831:Coordination Complexes; D005308:Fertilizers; D010710:Phosphates; D013501:Surface-Active Agents; D013725:Terbium