(For research use only, not for use in diagnostic procedures). In forensic drug analysis there is always a need for increased sensitivity to provide better detection of new synthetic substances in challenging casework. The capability to resolve very complex mixtures and provide confirmation of the identity of polar drugs and metabolites is the strength of Capillary Electrophoresis integrated with Mass Spectrometry. In this work we apply a sheathless interface for Capillary Electrophoresis-ESI-Mass Spectrometry (CESI-MS) for screening of 25 cathinone related designer drugs and metabolites in biofluids.

The sample preparation included a pre-treatment step using only a simple dilution of urine. The CE used a 90cm barefused silica, 150μm o.d., 30μm i.d. capillary, at 200-300V/cm, 2.4 to 2.8μamps at 25 °C. The background electrolyte (BGE) and conductive liquid were both 50mM Ammonium Formate, pH 2.85. Sample introduction was either Hydrodynamic; 16s at 34.5mBar or Electrokinetic; 10kV for 16s. The CE Instrument was a Beckman Coulter CESI 8000 coupled to an AB SCIEX 5600 TripleTOF^® mass spectrometer through a sheathless interface High Sensitivity Porous Sprayer (HSPS). The ESI Voltage applied to the interface was 1.2 to 1.8kV. The capillaries were initially conditioned with MeOH, water, 1N NaOH, water and BGE.

A sheathless HSPS was used to interface CE and ESI-MS. The drugs tested included 25 cathinone drugs and metabolites in urine. Acquired MS/MS spectra were searched against an accurate mass drug library for confident compound identification. Combining high resolution MS and MS/MS acquisition with Capillary Electrophoresis separation, allows for retrospective compound identification of the cathinones with highest confidence based on accurate mass product ion specificity, mass spectral library matching as well as mass error, isotopic profile and molecular formula finding. The LOQ values for all components were found to be less than 5ng/mL. Linearity was achieved between 5-1000ng/mL for most drugs and % RSDs for different analytes are reported to be less than 10 % in most cases.

A sheathless interface for Capillary Electrophoresis- ESI-Mass Spectrometry (CESI-MS) has shown to be a viable alternative for screening of 25 cathinone related designer drugs and metabolites in biofluids.