Determination of ascorbic acid via luminescence quenching of LaF3:Ce,Tb nanoparticles synthesized through a microwave-assisted solvothermal method

A novel approach for the rapid determination of ascorbic acid was developed based on the direct luminescence quenching of LaF3:Ce,Tb nanoparticles. The LaF3:Ce,Tb nanoparticles were synthesized via a microwave-assisted method with ionic liquids (BmimBF4) as the fluorine source. The as-prepared nanoparticles were uniformly ellipsoidal with an average size of about 12 nm. They are water soluble and highly fluorescent under 249 nm excitation. A new method for the rapid determination of ascorbic acid was established based on the large degree of overlap between the excitation spectrum of LaF3:Ce,Tb nanoparticles and the absorption spectrum of ascorbic acid. Ascorbic acid exhibits a broad band from 200 to 300 nm with the maximum absorption at 260 nm, which can absorb the excitation light of LaF3:Ce,Tb nanoparticles, consequently resulting in the luminescence quenching. The results showed a good inverse linear relationship between the luminescent intensity of LaF3:Ce,Tb nanoparticles and the concentration of ascorbic acid in the range 8.0 × 10−6 to 1.0 × 10−4 mol L−1 (R = 0.9995), with the detection limit of 2.4 × 10−6 mol L−1 and a RSD of 0.5% (5.33 × 10−5 mol L−1, n = 11). Compared with the standard redox titration method, our new method is effective for the determination of ascorbic acid.