DETECTION OF N,N'-DIPHENYL-N,N'-DIETHYLUREA (ETHYL CENTRALITE) IN GUNSHOT RESIDUES USING HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH FLUORESCENCE DETECTION

An HPLC with fluorescence detection method has been developed to detec t N,N'-diphenyl-N,N'-diethylurea (ethyl centralite, EC) in gunshot res idues. Residues were recovered with cotton wool swabs. Ethyl centralit e was extracted from swabs, cleaned, and hydrolysed to yield N-ethylan iline (NEA). Any N-ethylaniline was dansylated in alkaline buffer solu tion at 52 degrees C for 30 min. The derivative was analysed by revers ed-phase HPLC with fluorescence detection. The detection limit is 60 p g of NEA per injection. Accounting for the procedures of clean-up, hyd rolysis, and dilution, this equates to 670 pg of EC recovered from a h and swab. Three out of eleven types of gunpowders analysed were found to contain EC. Ethyl centralite was detected in cotton swabs sampled f rom a spent cartridge case and the shooting hand of a subject immediat ely after firing two rounds of revolver ammunition. The quantities of EC recovered from these swabs were shown to be 193.4 and 1.89 ng, resp ectively.