SOLUTIONS THAT MEET YOUR DEMANDS FOR FORENSIC TOXICOLOGY

Significance

Monitoring oxycodone, cocaine and their metabolites in biological fluids is critical for forensic toxicology and clinical pharmacology. Liquid chromatography–mass spectrometry (LC/MS) approaches offer sensitive, derivatization‐free analysis, simplifying workflows and improving throughput over traditional GC/MS methods.

Analytes and Matrices

Key analytes include:

• Oxycodone and metabolites: noroxycodone, oxymorphone, noroxymorphone
• Cocaine and metabolites: benzoylecgonine (BE), cocaethylene (CE), norcocaine
• Benzodiazepines: alprazolam, diazepam, nordiazepam, others
• Methadone, morphine, hydromorphone, codeine, hydrocodone, 6‐acetylmorphine

Matrices studied: human blood, plasma, and urine.

Sample Preparation

Biological specimens (typically 1 mL) are fortified with deuterated internal standards, buffered, and subjected to solid‐phase extraction (mixed‐mode SPE columns). Eluates are evaporated, reconstituted in mobile phase, and injected for LC/MS, omitting derivatization.

Chromatography

Rapid separations use 2.1×50–150 mm RRHT or StableBond SB‐C18 columns (1.8–3 μm particles) at elevated temperatures (30–60 °C). Mobile phases: aqueous ammonium formate or formic acid buffers and organic modifier (acetonitrile or methanol) under isocratic or short gradients (run times 5–9 min).

Mass Spectrometry

Five instrument platforms were compared:

• Single quadrupole (SQ) in selected ion monitoring (SIM) mode—quantitative, LOQs 5 ng/mL (cocaine, BE), 10 ng/mL (CE)
• Triple quadrupole (QQQ) in multiple reaction monitoring (MRM)—highest quantitative sensitivity (LOQs 0.5–2 ng/mL), confirmation by qualifier ion ratios
• Ion trap (IT) in full‐scan MS/MS and MS3 (AutoMSn)—excellent qualitative screening, library matching of fragmentation patterns
• Time‐of‐flight (TOF)—accurate‐mass full scan MS quantification (±2 ppm), and screening by exact mass EICs (±10 ppm)
• Quadrupole TOF (QTOF)—accurate‐mass MS and MS/MS identification, quantitative capabilities in MS mode

Key Performance

• Linearity: R2 > 0.99 over three or more concentration decades
• Precision: CV < 10% at low‐ng/mL levels
• Limits of quantitation: down to 0.02–0.5 ng/mL depending on analyte and instrument
• Fast cycle times: 5–9 min including re‐equilibration in some methods
• Case samples: real postmortem and DUID blood/urine analyses demonstrated accurate quantitation and confirmation across platforms

Conclusions

LC/MS allows comprehensive analysis of opioids, cocaine and metabolites, and benzodiazepines without derivatization. QQQ provides best quantitative sensitivity and confirmation; SQ offers simple, routine quantification; IT excels in qualitative MSn screening; TOF/QTOF adds accurate‐mass identification and screening capabilities. Choice of MS depends on required sensitivity, confirmation, and screening breadth.

References

[1] Broussard et al., Clin. Chem. 1997;43:1029–1032
[2] Slawson et al., J. Anal. Toxicol. 1999;23:468–473
[3] Feyerherm et al., Agilent App. Note 988-4805EN