Drugs of Abuse from Plasma

Matrix: Bovine Plasma (sodium citrate anti-coagulant), 1.3mL; adjusted to pH 11.5 with 0.7mL sodium hydroxide

Extracting Phase: PDMS (25µL ILE Cap)

Compounds: Cocaine (500ng/mL), Methamphetamine (500ng/mL), Amphetamine (500ng/mL)

Immobilized Liquid Extraction (ILE) Caps provide a simple method for extracting drugs of abuse from plasma for analysis by GC-MS. A series of 1.3mL bovine plasma samples were spiked with 1 microgram of cocaine, methamphetamine and amphetamine in 40mL VOA vials. The samples were buffered with 0.7mL sodium hydroxide to a pH of 11.5, and salted to 10% with potassium carbonate. The sample vessels were sealed with 25µL PDMS ILE Caps, inverted, and agitated by a mechanical wrist shaker for 1 hour to allow analytes to partition from the sample into the immobilized solvent phase.

The ILE Caps were removed from the sample vessels and placed on high-recovery vials containing 150µL acetone. These vials were inverted and agitated for 20 minutes to allow analytes to partition from the immobilized phase into the acetone. The resulting extracts were analyzed by an HP-5971 GC/MS in SIM mode with a 30m x 0.25mm i.d. x 0.25µm VB-5 column. The following table shows Log P for each compound, and displays the efficiency with which it was extracted:

Phase: PDMS            Matrix: Plasma