Related Experiment Videos
Adsorption losses from urine-based cannabinoid calibrators during routine use
J A Blanc1, V A Manneh, R Ernst
1Development Department, Syva Co., San Jose, CA 95161-9013.
Clinical Chemistry
|August 1, 1993
Summary
Cannabis metabolite delta 9-THC adsorbs to surfaces, causing inaccurate drug test calibrators. Proper pipette use and minimizing surface-to-volume ratios in analyzer cups significantly reduce this analyte loss.
Area of Science:
- Forensic Toxicology
- Analytical Chemistry
Background:
- 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (delta 9-THC) is the primary urine metabolite of cannabis.
- Delta 9-THC is crucial for calibrating cannabinoid immunoassays.
- The hydrophobic nature of delta 9-THC leads to adsorption onto solid surfaces, compromising assay accuracy.
Purpose of the Study:
- To quantify cannabinoid loss from calibrator solutions due to handling.
- To identify specific handling techniques contributing to analyte loss.
- To develop strategies for minimizing delta 9-THC adsorption during testing.
Main Methods:
- Quantification of cannabinoid loss using immunoassay techniques.
- Utilizing radioactive tracers to measure analyte loss.
- Analyzing the impact of different pipette types on adsorption.
- Assessing the effect of surface-to-volume ratio in analyzer cups.
Main Results:
- Significant delta 9-THC losses were observed during calibrator handling.
- Analyte loss is influenced by the type of pipette used for solution transfer.
- The surface-to-volume ratio of the calibrator solution in the analyzer cup affects adsorption.
- Losses were confirmed through both immunoassay and radioactive tracer methods.
Conclusions:
- Handling techniques are a primary cause of analyte loss in delta 9-THC calibrators.
- Employing specific pipettes and optimizing surface-to-volume ratios can minimize adsorption.
- Implementing suggested handling procedures enhances the accuracy of cannabinoid immunoassays.