FORENSIC CHEMISTRY LABORATORY MANUAL

by R.Q. Thompson; Oberlin College

ANALYSIS OF A SIMULATED BLOOD SAMPLE FOR DRUGS

Objective

To determine if a blood sample contains illicit drugs (from a short list of possibilities).

 

Sample

Simulated blood plasma with added illicit drug at a concentration of about 0.30 µg/mL. Prepare a fresh sample the day of the testing; the sample is not stable for more than a couple of days, even when stored in the refrigerator. The drug is chosen from a short list, provided to the students. Drug standards may be purchased without a DEA license (e.g. from Sigma-Aldrich) .

 

Reagents

Drug standard (Sigma-Aldrich); methanol; 0.050 M, pH 6.0 phosphate buffer; 0.10 M HCl; 80:18:2 mixture of ethyl acetate:methanol:ammonium hydroxide

 

Standard Reference Material

 

None

 

Method

Solid phase extraction ; gas chromatography - mass spectrometry

 

Special equipment

Capillary gas chromatograph-mass spectrometer with mid-polar column (e.g. DB-5, phenyl methyl silane, 30 m x 0.25 mm x 0.25 µm); 10-µL syringe; 2-mL chromatography vials with screw caps; 3-mL, mixed-mode (C8 & strong cation exchanger) solid phase extraction (SPE) cartridges (e.g. Strata Screen C from Phenomenex); vacuum manifold; aluminum heating block and supply of nitrogen gas for evaporating solvents

 

Procedure

For instructor (detailed) ; For student (brief)

 

Typical results

Total ion chromatogram of 0.50 µg/mL drug sample (cocaine) processed by SPE; 5µL injection of SPE eluate at 20:1 split; 1 mL/min helium flow; temperature programmed separation; ion trap mass analyzer.

Mass spectrum of suspected drug (cocaine) from chromatogram above. Result of library search of suspected cocaine spectrum.