Analysis of drugs of forensic interest with Capillary Zone Electrophoresis / Time-of-Flight Mass Spectrometry based on the use of non-volatile buffers

The present work is aimed at investigating the influence of the background electrolyte composition and concentration on the separation efficiency and resolution and mass spectrometric detection of illicit drugs in a CZE-ESI-TOF MS system. The effect of phosphate, borate and Tris buffers on the separation and mass spectrometry response of a mixture of 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, methadone, cocaine, morphine, codeine and 6-monoacethylmorphine was studied, in comparison with a reference ammonium formate separation buffer. Inorganic non volatile borate and Tris buffers proved hardly suitable for CE-MS analysis, but quite unexpectedly ammonium phosphate buffers showed good separation and ionization performances for all the analytes tested. Applications of this method to real samples of hair from drug addicts are also provided.