Total internal reflected resonance light scattering determination of chlortetracycline in body fluid with the complex cation of chlortetracycline-europium-trioctyl phosphine oxide at the water/tetrachloromethane interface

A highly selective method of chlortetracycline (CTC) is proposed on the basis of the measurements of total internal reflected resonance light scattering (M-RLS) at water/tetrachloromethane (H2O/CCl4) interfaces. In the pH range of 7.54-8.14, the interaction of the binary complex of Eu(III)/CTC in the presence of trioctyl phosphine oxide (TOPO) occurs at the H2O/CCl4 interface, resulting in greatly enhanced TIR-RLS, signals with the maximum peak located at 340 nm. The enhanced TIR-RLS intensity is in proportion to the CTC concentration in the range 0.98 similar to 20.0 x 10(-7) mol/L. The limit of detection is 9.8 x 10(-9) mol/L. Synthetic samples and body fluid samples including human urine, human serum, and fresh milk were determined with the recovery of 95.4-106.4% and RSD of 2.9-3.9%.