2018 年 30 巻 2 号 p. 175-187
A high-throughput method was developed to analyze five barbiturates （phenobarbital, cyclobarbital, amobarbital, secobarbital, and thiopental） and a metabolite in human body samples using a new Monolithic C18 gel-packed Spin Tip and ultra-performance liquid chromatography （UPLC）-quadrupole-time-of-flight （Q-ToF） mass spectrometry （MS）. Plasma （20µl） or urine （100µl） samples spiked with the five barbiturates and 5-（4-methylphenyl）-5-phenylhydantoin （internal standard, IS） were mixed with distilled water. The mixture was extracted using the Monolithic C18 Spin Tip, and the analytes retained on the C18 phase were then eluted with methanol. The eluate was injected directly into an analytical column （Waters Acquity BEH C18, 50mm×2.1mm i.d., particle size 1.7µm）, and quantified by Q-ToF-MS with negative-ion electrospray ionization （ESI）. Good separation and clear peak shapes of the five drugs were achieved within an analysis time of 6min, including the extraction time. All drugs spiked in the plasma showed recoveries of 86-98％. The regression equations for the five drugs showed excellent linearities in the range of 5-500ng/20µl of plasma, with limits of detection and i-Fit of 1ng/20µl. The method was also successfully applied to determine the level of amobarbital and its metabolite in human plasma and urine, respectively, after oral administration to a volunteer. This new method could be applied widely in the clinical and forensic fields for the quantitative determination of drugs and metabolites.
