Oral fluid collection: the neglected variable in oral fluid testing.

Area of Science:

• Forensic Toxicology
• Analytical Chemistry
• Clinical Chemistry

Background:

• Oral fluid (OF) is a promising alternative specimen for drug testing due to ease of collection.
• OF drug concentrations may reflect blood-drug levels, offering value in clinical and forensic settings.
• The impact of OF collection procedures on drug detection and quantification is often overlooked.

Purpose of the Study:

• To investigate the effects of various oral fluid collection methods on drug concentrations.
• To evaluate the influence of collection techniques, devices, and storage conditions on drug stability and recovery.
• To assess the potential of endogenous markers for oral fluid specimen validity.

Main Methods:

• Controlled clinical study comparing different stimulation methods (acidic, mechanical, commercial devices) for codeine collection.
• In vitro experiments assessing collection volume, recovery rates, and drug recovery (amphetamines, opiates, cocaine, THC, PCP) from commercial devices.
• Evaluation of THC stability in collection buffer under different storage conditions (frozen, refrigerated, room temperature).
• Preliminary experiments on the effect of water rinsing on IgG concentration as a specimen validity marker.

Main Results:

• Collection technique significantly affected codeine OF concentrations, with non-stimulating methods yielding higher concentrations than stimulated methods or commercial devices.
• In vitro recovery rates for various drugs varied considerably between commercial devices (e.g., amphetamines 16-59%, THC 0-53%).
• THC stability was good when frozen but marginal under refrigeration and poor at room temperature.
• Water rinsing did not significantly reduce IgG concentration below proposed validity criteria.

Conclusions:

• Collection method, device type, and storage conditions are critical variables that can significantly alter oral fluid drug concentrations.
• These variables can confound the interpretation of oral fluid drug test results.
• Further research and standardization are needed to address these collection-related effects in oral fluid drug testing.