Determination of serum diclofenac by high-performance liquid chromatography by electromechanical detection.

Diclofenac was isolated from plasma by double extraction with organic solvent. Chromatography was performed on Lichrosorb NH2 column with acetonitrile and perchloric acid (0.0025 mol/l; 35:65, v/v) as the mobile phase (flow rate 0.9 ml/min). The electrochemical detector was operated at +900 mV and sensitivity of 5-10 nA. The sensitivity of the method was 10 micrograms/l and the coefficients of variation below 10% in the entire range of the concentration in a dose interval.