A Dilute-and-Shoot LC-MS Method for Quantitating Opioids in Oral Fluid

Area of Science:

• Clinical Chemistry
• Forensic Toxicology
• Analytical Chemistry

Background:

• Opioid testing is a major segment of pain management clinical testing.
• Oral fluid (OF) analysis for opioids is gaining traction due to its non-invasive nature.
• Traditional OF opioid testing methods involve time-consuming sample clean-up and concentration steps.

Purpose of the Study:

• To develop and validate a rapid, high-throughput quantitative method for eight common opioids and their metabolites in oral fluid.
• To eliminate the need for extensive sample manipulation in oral fluid opioid testing.
• To provide a more efficient and cost-effective alternative to existing analytical methods.

Main Methods:

• A 'dilute-and-shoot' approach was employed, involving a 10-fold dilution of oral fluid in methanol/water.
• Analysis was performed using an Agilent LC system coupled with an AB SCIEX 4500 mass spectrometer.
• A phenyl-hexyl column was utilized for chromatographic separation, achieving a 2.2-minute LC gradient and a 2.9-minute cycle time.

Main Results:

• The method successfully quantified eight common opioids and metabolites (codeine, morphine, hydrocodone, hydromorphone, norhydrocodone, oxycodone, noroxycodone, oxymorphone) in oral fluid.
• Baseline separation of isobaric opioids was achieved.
• The validated calibration range was 2.5-1,000 ng/mL, with only 100 μL of sample required.

Conclusions:

• The 'dilute-and-shoot' method offers a significantly faster and more efficient alternative for oral fluid opioid testing.
• This approach eliminates costly and time-consuming extraction steps, making it ideal for high-throughput laboratories.
• The method meets all analytical requirements while simplifying the testing process.