Flow injection amperometric detection based on ion transfer across a water-solidified nitrobenzene interface for the determination of tetracycline and terramycin

Abstract

An accurate, convenient and fast method is described for the determination of tetracycline and terramycin in drugs by flow injection amperometric detection based on ion transfer across a water-nitrobenzene interface solidified with poly(vinyl chloride) and agar. When a constant potential is applied both antibiotics transfer across the interface, the process being facilitated by protons, with a linear current response for 2–200 µM solutions of tetracycline and 5–300 µM solutions of terramycin. The coefficients of variation for 22 replicate injections of 0.2 mM solutions of tetracycline and terramycin are 1.2 and 2.5%, respectively. The results obtained are in good agreement with those given by a biological assay (the relative standared deviation is less than 1%). A total of 60 samples could be determined in 1 h.