NCJ Number
226636
Journal
Problems of Forensic Sciences Volume: 71 Dated: 2007 Pages: 313-322
Date Published
2007
Length
10 pages
Annotation
This study developed, validated, and compared chromatographic methods (high performance liquid chromatography [HPLC] and gas chromatography-mass spectrometry [GC-MS]) for the detection of Delta-9-tetrahydrocannabinol (delta-9-THC) and Delta-9-tetrahydrocannabinolic acid (delta-9-THCA-A).
Abstract
Study findings show that both developed methods can be used in routine analysis for distinguishing drug type from fiber-type cannabis. They can be applied in measuring the total delta-9-THC concentration in cannabis hemp and other cannabis products, including cannabis resin (hashish). Samples of dry plant material (0.5 g) were extracted with 5ml methanol overnight (16 hours). The separation of the sample components was performed by HPLC on an RP-18e Chromolith column (5um, 100 mm) at 40 degrees C with isocratic elution. The mobile phase consisted of a mixture of water that contained 100 ml phosphoric acid per 1 liter (pH 3) and acetonitrile (70:30). GC-MS separation of sample components was carried out on an HP-5MS (30 m x 0.25 mm x 0.25 um) column. Acquisition was performed in the full scan mode. The limits of detection (LOD) for HPLC were 0.00030 percent (converted to dry hemp matter) for delta-9-THC and 0.00068 percent for delta-9-THCA-A. The calibration curves were linear both for delta-9-THC and THCA-A (r=0.999) in the tested range: 0.05 percent (2.5 mg/ml) up to 2.0 percent (100 mg/ml). The intra-assay and inter-assay precision, expressed as the percentage coefficient of variation (CV), were 3.5 percent and 8.2 percent for delta-9-THC and 3.4 percent and 8.4 percent for delta-9-THCA-A. The LOD for delta-9-THC obtained by GC-MS was 0.015 percent. The calibration curve was linear in the range from 0.1 percent up to 0.8 percent. The GC-MS intra-assay precision expressed as CV was 15.3 percent, and the inter-assay precision was 21.3 percent. 10 figures, 2 table, and 3 references