VOLTAMMETRIC STUDIES OF A PSYCHOTROPIC-DRUG WITH NITRO-GROUPS - DETERMINATION OF FLUNITRAZEPAM IN URINE USING HMDE

The adsorption behaviour of flunitrazepam at the hanging mercury drop electrode was studied by staircase voltammetry and by adsorptive strip ping differential pulse voltammetry. Flunitrazepam is adsorbed in the whole potential range, from the most positive values up to the reducti on potential. Flunitrazepam reduction product is also adsorbed. The ti me dependence of the voltammetric response proves that a diffusion-con trolled adsorption takes place. Flunitrazepam can be determined (down to nanomolar levels) by using adsorptive preconcentration prior to the differential pulse voltammetric scan. An application of such a method to flunitrazepam determination in human urine is described. The detec tion limit was 30 ng per milliliter of urine with a 20-sec accumulatio n time; the mean relative standard deviation was lower than 3.2% and t he mean recovery 97.8%.