A Comparison of Several LC/MS Techniques for Use in Toxicology

The analytical capabilities of various liquid chromatography/mass spectrometry (LC/MS) instruments are compared in the study of illicit and prescription drugs in blood. The blood samples analyzed include postmortem and driving under the influence of drugs (DUID). The presence of drug compounds in these samples was previously confirmed using gas chromatography/mass spectrometry (GC/MS). In this work, the LC conditions are common among the different types of mass spectrometers used. The mass spectrometers used include the single quadrupole (SQ), the timeof-flight (TOF), the ion trap (IT), the triple quadrupole (QQQ), and the quadrupole timeof-flight (QTOF). Both LC and MS instrumentation are Agilent. In analyzing the different samples for the presence of several drug compounds, the advantages and disadvantages of each type of instrumentation are demonstrated. For example, the IT, TOF, and QTOF mass spectrometers are shown to be excellent devices for qualitative screening and identification. On the other hand, the SQ and QQQ mass spectrometers are excellent devices for quantitative targeted confirmation. And yet, the converse is somewhat true in that the TOF and QTOF instruments may also be useful for quantification, though not as sensitive as an instrument like the QQQ. Drugs of interest in the blood samples include benzodiazepines, methadone, and cocaine metabolites. Authors Michael Zumwalt Agilent Technologies, Inc. 9780 S. Meridian Blvd. Englewood, CO 80112 USA John Hughes Agilent Technologies, Inc. 6612 Owens Drive Pleasanton, CA 94588 USA Greg Kilby Agilent Technologies, Inc. 2850 Centerville Road Wilmington, DE 19808 USA Jeri Ropero-Miller and Peter Stout RTI International 3040 Cornwallis Road Raleigh-Durham, NC 27709 USA H. Chip Walls University of Miami School of Medicine 1611 NW 12th Avenue Miami, FL 33136 USA Application Note Toxicology