Analysis of stimulants and related compounds by automated on-line in-tube SPME/LC/MS

A simple and rapid method for the analysis of amphetamines and their 3,4-methylenedioxy derivatives was developed by automated in-tube solid-phase microextraction/liquid chromatography/electrospray ionization mass spectrometry (in-tube SPME/LC/ESI-MS). Optimum In-tube SPME conditions for these drugs were 15 draw/eject cycles of 35 μL of sample in Tris-HCl (pH 8.5) using Omegawax 250 capillary column. The drugs extracted by the capillary column were easily desorbed by mobile phase flow, and carryover was not observed. Using in-tube SPME/LC/ESI-MS with selected ion monitoring, the calibration curves of these drugs were linear in the range of 2-100 ng/mL with correlation coefficients above 0.9985 (n=18), and the detection limits (S/N=3) were 0.4-0.8 ng/mL. This method was successfully applied to the analysis of urine samples without interference peaks and with recoveries above 80%.