Spectrofluorimetric determination of lecithin using a tetracycline–europium probe

Trace amount of lecithin (PC) was determined in the buffer solution of pH 5.7, using tetracycline (TC)–europium ion (Eu3+) as a fluorescent probe. PC can remarkably enhance the fluorescence intensity of the TC–Eu3+ complex at λ = 612 nm and the enhanced fluorescence intensity of Eu3+ is in proportion to the concentration of PC. Optimum conditions for the determination of PC were also investigated. The linear range and detection limit for the determination of PC are 4.0 × 10−7 to 1.4 × 10−5 mol/L and 3.9 × 10−8 mol/L. This method is simple, practical and relatively free of interference from coexisting substances and can be successfully applied to assess PC in serum samples. Moreover, the enhancement mechanism of the fluorescence intensity in the TC–Eu3+ system, the TC–Eu3+–PC system, and the TC–Eu3+–PC–sodium dodecyl benzene sulfonate (SDS) system is also discussed.