Drug Screening Method for over 375 Drugs in Blood Using Size Exclusion Chromatography Pipette Tips
SOFT 2024 Poster Presentation
Development and Validation of Liquid Chromatography Quadrupole/Time of Flight Drug Screening Method using INTip Size Exclusion Chromatography at ANSI/ASB Recommended Screening Thresholds
Presented by South Carolina Law Enforcement Division
Abstract
In forensic toxicology, the drug screening process is a critical component of case examinations. Many widely used screening methodologies exhibit analytical limitations. Advancements in instrumentation have prompted a pursuit of screening techniques that offer an expanded scope, improved sensitivity and specificity, and reduced sample size, all while preserving sample integrity. By employing size exclusion chromatography (SEC), it is possible to enhance sensitivity for low-level analytes by mitigating biological matrix effects. The integration of SEC for sample preparation with liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC/QTOF) for analytical detection facilitates the identification of analytes at the thresholds recommended by ANSI/ASB standards. This validation of over 375 analytes includes the identification of carboxy-THC and barbiturates through the analysis of a single extracted aliquot using both positive and negative modes. This Auto MS/MS LC-QTOF method provides significantly more comprehensive information compared to the current implanted immunoassay technique fundamentally transforming our approach to case work in the future.
Method
| 1 | Aliquote 0.5 mL blood sample, add internal standard |
|---|---|
| 2 | Protein precipitation; centrifuge then transfer to clean vial and dried to completion under nitrogen |
| 3 | Swell resin bed according to specifications for 1500 Da Size Exclusion Chromatography (SEC) tips from DPX Technologies |
| 4 | Reconstitute sample, vortex and add sample to swollen gel resin bed of SEC pipette tip. Let gravity flow |
| 5 | After all liquid absorbed into resin bed, wash SEC tip with 20:80 methanol: deionized water and let gravity flow from tip to waste |
| 6 | Transfer tip to new vial. Elute with 50:50 methanol: deionized water and dry under nitrogen to completion |
| 7 | Sample reconstituted in 100 µL of 95:5 mobile phase A and mobile phase B |
About INTip Size Exclusion Chromatography
Unique pipette tip design for automated group separation of complex sample mixtures and patent-pending INTip Swelling method.