Determination of flunitrazepam by differential-pulse voltammetry using a bentonite-modified carbon paste electrode

Abstract

A method is described for the determination of flunitrazepam using a bentonite-modified carbon paste electrode. Flunitrazepam is adsorbed on the electrode in an open circuit (pH 3.8) and determined in 0.5 M KNO3 by differential-pulse voltammetry.The calibration is linear for values between 0.2 and 4.0 µg ml–1. The detection and determination limits were about 0.04 and 0.13 µg ml–1 of flunitrazepam, respectively. The measurements have a relative standard deviation of 1.8% and a relative error of 1.6%. It is possible to determine directly 1.5 µg ml–1 of flunitrazepam in serum and urine with a relative standard deviation of <6.0% when compared with the same determination in a solution without serum.