HPLC Coupled with Quadrupole
Mass Spectrometry and
Forensic Analysis of Cocaine
Analysis of Cocaine
• Important for forensics
• Samples
• An unknown powder
• Could contain other
components
• A human specimen
• Fluids (urine, blood
saliva)
• Hair
C17H21NO4
Molecular weight: 303.353 g/mol
HPLC: High performance liquid
chromatography
• Sample injected using
pressurized system
• Compounds travel through
column at different rate
– Interact with stationary phase
• Detection
– Traditionally by UV absorption
– More recently Mass
spectrometry
• Better identification of unknowns
Typical Silica bead with
C18 chains projecting off
Reverse Phase HPLC
• Stationary Phase: small silica particles with long
hydrocarbons chains attached (non polar)
• Mobile Phase: solvent, typically a water/alcohol
solution (polar)
Red compound is less polar than Blue compound
Red compound is present in a lower quantity
Example HPLC Chromatograms
Retention time differences for cocaine and some of its metabolites
Mass spectrometry
• Ion Source
– Compound vaporized into gas phase
– Energy added to ionize the compound
• Excess energy may also fragment compound
– Most Common Method for cocaine: electrospray
• Mass Analyzer
– Fragments sorted based on mass/charge ratios
– Ions detected
Quadrupole Mass Spectrometry
• Apply voltages to 4 parallel rods
• Create an electric field
• Can change voltages to scan through m/z ratios
Resonant ions will make it
through to the detector
Non-resonant ions will be
neutralized by hitting rod
Mass Spectrometric identification of
unknowns
•Quadrupole MS allows distinction of compounds with similar m/z
•Compounds can also be distinguished by fragmentation patterns
Parent compound
Daughter ions
after fragmentation
Example Mass Spectra Results
Cocaine and its
metabolites have
different mass spectra
and fragmentation
patterns
Oral Samples
(Subject’s Saliva)
Applications
• Blood Gas Analysis
• Allows for in vivo testing of gases present in the blood
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Analysis of stomach contents of overdose victims
Drug Profiling
Hair testing
Identification of unknown crime scene
specimens
Recent Studies
• Detection in Human Specimens
– Optimize separation and codetection of several
different drugs in urine
• Detection in Unknown Powder
– Cocaine was identified in presence of metabolites
and other drugs from benzoylecgonine