Luminescence determination of sodium and potassium using molecular sensors on the basis of terbium(III) complexes of 4-carboxybenzocrown ethers

As is well known, a certain ratio of potassium and sodium concentrations is necessary for the normal activity of an organism. Disturbances of the sodium-potassium balance lead to the violations [...]
The spectral luminescent properties of terbium(III) complexes of 4-carboxybenzo- 15-crown-5 ([L.sub.1]) and 4-carboxybenzo-18-crown-6 ([L.sub.2]) are studied. The quenching of the luminescence of lanthanide by alkali metal ions is discovered, which is referred to as the formation of mixed Tb(III)-Li-[Na.sup.+] and Tb(III)-[L.sub.2]-[K.sup.+] complexes. The complexes are useful as molecular sensors for the luminescence determination of [Na.sup.+] and [K.sup.+] with the detection limits 1.5 and 25.0 µg/mL. Using the Tb(III)-Li complex, sodium can be determined in the presence of a 1000-fold excess of potassium. The developed procedures are utilized for the determination of KCl in the Kalipoz medication in tablet form and the total sodium salts (NaCl, NaHC[O.sub.3]) in the Trisol solution for infusions. Keywords: luminescence analysis, terbium(III) complexes, 4-carboxybenzocrown ethers DOI: 10.1134/S1061934810121032