Confirmatory Testing, Chromatography & Forensic Drug Analysis – Comprehensive Study Notes

Purpose: Conclusive structural identification of chemical/biological species with minimal false positives; considered “gold-standard” despite higher costs.
Common Platforms: GC–MS, HPLC, LC–MS, FT-IR, NMR.
SWGDRUG Requirements: Specific combinations of Category A (structural, e.g., MS), B (comparative, e.g., GC), and C (preliminary, e.g., colour tests) techniques.

Mechanism: Differential interaction with stationary vs. mobile phases controls migration rate.
Modes: Adsorption, Partition, Size-Exclusion, Affinity.

Advantages: High resolving power, rapid analysis, quantitative accuracy, automation-amenable.
Instrument Layout: Solvent ➜ pump ➜ injector ➜ column ➜ detector ➜ data system.
Columns: Precision-bore stainless-steel (e.g., $10 ext{–}30 ext{ cm}$ long), packed with specific materials (e.g., silica, C18-bonded phases).
Solvents: Particle-free, degassed, UV-clean; often water/methanol/acetonitrile mixtures; can include buffers or additives.
Elution: Isocratic (constant mobile phase) or Gradient (changing organic strength).
Modes: Normal-phase (polar stationary, non-polar mobile), Reversed-phase (non-polar stationary, aqueous/organic mobile), Ion-exchange, Chiral, Affinity, Size-Exclusion.
Reversed-Phase Control: Depends on surface chemistry (e.g., C18), mobile-phase composition, pH, and additives.

Metrics: Void time ( $t ext{0}$ ), retention time ( $t ext{r}$ ), capacity factor ( $k'$ ).
Resolution ( $R ext{s}$ ): Measures peak separation ( $R ext{s} = 1.5$ for baseline separation).
Band Broadening: Dispersion of analytes due to diffusion and mass-transfer limitations.
Resolution Increase: Change column, optimize solvent, use gradient elution.

Enantiomers (e.g., S and R-methamphetamine) have identical bulk physical spectra but distinct legal statuses (illicit vs. legal).
Solution: Chiral Stationary Phases (CSPs) provide differential retention for enantiomers.

Uses: Drug identification, quantification, impurity profiling, cutting-agent identification.
In law, quantitative results influence sentencing severity (e.g., Misuse of Drugs Act 1971).

QC: Prevents cross-contamination, uses calibrants and standards; includes internal/external programs.
QA: Ensures instrument function, sample integrity, data validation; aligns with ILAC 17025.
Chain of Custody: Documented process ensuring sample integrity from submission to court.

Risk: Crash risk rises exponentially with BAC; specific limits vary by jurisdiction/licence class (e.g., UK/Australia 0.05 ext{%}).
Penalties: Vary by BAC and prior offenses, including disqualification, fines, and imprisonment.
Breathalyser: Electrochemical fuel-cell or IR spectrophotometric detection (e.g., $ext{CH}2 ext{CH}2 ext{OH} + ext{O}2 ightarrow ext{CH}3 ext{COOH} + ext{H}_2 ext{O}$ ).

Processes: Absorption (upper intestine), Distribution (systemic), Elimination (hepatic metabolism; minor excretion).

Testing: Random roadside saliva testing (e.g., QLD since 2007 for $ext{THC}$ , methylamphetamine, MDMA).
Process: Saliva stick ➜ if positive, station confirmatory test.
Penalties: Fines, suspension, imprisonment (e.g., QLD first offence).

Road deaths involving alcohol remain a concern in QLD.
Victorian drug testing shows high positivity for methylamphetamine, cannabis, and MDMA.

Definitions: Licit (legal), Controlled Licit (prescription), Illicit (banned).
Classification: Depressants, hallucinogens, stimulants, etc.
Trends: Decline in traditional drugs, rise in Novel Psychoactive Substances (NPS).
Persistence: Varies widely by drug and sample type (e.g., cannabis in urine up to 30 days, hair >90 days).

Overview: Rapid emergence of new compounds, often derivatives of banned substances (“cat-and-mouse”).
Classes: Phenethylamines (amphetamine, MDMA), Cathinones (mephedrone), Synthetic cannabinoids, Tryptamines, Fentanyl analogues.

Challenges: Accurate quantification for legal penalties; balancing public safety with individual freedoms; ongoing debates on BAC limits.