Direct detection of morphine in human urine by surface-ionization mass spectrometry

Detection and analysis of drugs-of-abuse in biological fluids are the essential tasks for the law enforcement, forensic toxicology, doping research and social health. In this work, we developed a surface-ionization mass spectrometry method for direct detection of trace amount of morphine spiked in blank urine. The mass-spectrometric analysis of spiked samples was carried out without preliminary extraction and chromatographic separation. It was found out that the major fragment ions at m/z 144, 146 could be served as indicator lines of morphine spiked in blank urine. Limit of detection of morphine spiked in blank urine was 100 pg (50 ng/ml), and a linear range of calibration curve was more than two orders of magnitude. The spiked samples were also analyzed by gas chromatography-mass spectrometry without preliminary extraction and derivatization procedures. No morphine was found in the spiked samples. The experimental data show that the high selectivity of the surface ionization can be allowed to direct analysis of morphine spiked in blank urine without its preliminary extraction and chromatographic separation.