On-Line Immunoaffinity Extraction-Coupled Column Capillary Liquid Chromatography/Tandem Mass Spectrometry: Trace Analysis of LSD Analogs and Metabolites in Human Urine
Analytical Chemistry – January 01, 1996
Source: OpenAlex
Summary
An innovative method using online immunoaffinity extraction with capillary liquid chromatography and tandem mass spectrometry has achieved groundbreaking sensitivity in detecting LSD and its metabolites. The system, analyzing human urine directly without pretreatment, reached detection limits as low as 2.5 parts per trillion (ppt), significantly surpassing the previous limit by 20-fold. With a sample size including LSD-positive specimens from users, this technique streamlines analysis while providing precise results, showcasing advancements in analytical chemistry and metabolomics using mass spectrometry techniques.
Abstract
An on-line immunoaffinity extraction-coupled column capillary liquid chromatography/tandem mass spectrometry (IAE/LC/LC/MS/MS) method is described. The system involves three columns, a 2.1-mm-i.d. protein G immunoaffinity column with noncovalently immobilized antibody specific to the analytes of interest, a packed capillary trapping column, and a packed capillary analytical column. With use of a short packed capillary trapping column, the protein G column could be operated at flow rates of 2.5-4 mL/min while the packed capillary analytical column was maintained at a flow rate of 3.5 microL/min. Human urine diluted 1:1 with phosphate-buffered saline was pumped directly onto the immunoaffinity column without pretreatment and was analyzed by electrospray mass spectrometry following the column switching process. Sample handling and transfer procedures were eliminated. The system was optimized and evaluated for the determination of LSD, its analogs, and metabolites in spiked human urine at low part-per-trillion (ppt) levels using mass spectrometric detection. LSD-positive human urine specimens from LSD users were also analyzed. Concentrations as low as 2.5 ppt of LSD and several of its analogs were detected in spiked human urine using IAE/LC/LC/MS/MS/. This is 20-fold below our previous limit of detection using solid phase extraction and LC/MS/MS.