Courtesy of Supelco Inc.
Figure 42. Chromatograms of Tetrahydrocannabinol Car-boxylic Acid from Urine
The chromatograms obtained from a urine sample and a reference standard by this procedure is shown in figure 42. This is a typical application for liquid chromatography using a solid phase extraction cartridges. It is seen that the tetrahydrocannabinol carboxylic acid is clearly and unambiguously separated from the contaminating materials with an extraction efficiency of over 90%. The chromatographic conditions were as follows.
| Column | LC 18 |
| Column Length | 25 cm |
| Column Diameter | 4.6 mm |
| Column Packing | C18 Reverse Phase, (octadecyldimethyl chain) |
| Mobile Phase | 55% acetonitrile 45% aqueous 1% acetic acid |
| Flow-Rate | 2.5 ml/min. |
| Detector | UV adsorption at 280 nm |
| Sample Volume | 100ml containing 500 ng tetrahydrocannabinol |
