Europium-sensitized Chemiluminescence of System Tetracycline–H2O2–Fe(II)/(III) and Its Application to the Determination of Tetracycline

Chemiluminescence (CL) of the reaction system tetracycline–H2O2–Fe(II)/(III)–Eu(III) was used for the determination of tetracycline hydrochloride in water, pharmaceutical preparations, and honey. The CL spectrum registered for this system shows emission bands typical of Eu(III) ions, with a maximum at λ ∼ 600 nm, corresponding to the electronic transitions of 5D0 → 7F1 and 5D0 → 7F2. A strong chemiluminescence intensity characteristic of europium(III) ions in the system tetracycline–H2O2–Fe(II)/(III)–Eu(III), as contrasted to the emission of the system tetracycline–H2O2–Fe(II)/(III) without Eu(III), proves that the Eu(III) ion plays the role of a chemiluminescence sensitizer, accompanying tetracycline oxidation in the Fenton system (H2O2–Fe(II)/(III)). A linear dependence was observed for the integrated CL light intensity on the tetracycline concentration in the range of 2 × 10−7 to 3 × 10−5 mol l−1 with the detection limit of 5 × 10−8 mol l−1 in aqueous solution.