Optimization of CE-ESI-MS parameters for the analysis of ecstasy and derivatives in urine

Capillary electrophoresis (CE) was interfaced with a quadrupole mass spectr ometer, using pneumatically-assisted electrospray ionization (ESI) in order to analyze Ecstasy and derivatives in urine. The influence of the sheath l iquid composition, including the type and the percentage of the organic sol vent, as well as the nature of the conductive acid modifier, were examined in order to find optimal coupling conditions. A fractional factorial design was also used to optimize the electrospray experimental parameters, such a s the nebulizing gas pressure, the electrospray voltage, the drying gas flo w rate, the drying gas temperature, the skimmer voltage, and the sheath liq uid flow rate. The separation conditions were optimized in terms of tempera ture, electrolyte concentration, percentage of organic modifier, as well as capillary type, Finally, the optimal CE-ESI-RIS conditions were applied to the analysis of Ecstasy and other related amphetamines in urine samples, f ollowing a liquid-liquid extraction procedure.