Background: In clinical and forensic toxicology, fast and specific methods are needed for the screening of different classes of drugs. A complete general unknown screening procedure was developed using turbulent flow chromatography with electrospray ionization and Orbitrap mass spectrometry.
Methods: After protein precipitation, samples were injected directly into the turbulent flow chromatographic system and analyzed with an Orbitrap mass spectrometer. The Exactive® operated in positive and negative modes with alternated high collision dissociation in order to obtain characteristic fragments. We built a library containing 616 compounds by analyzing a reference standard for all the molecules.
Results: Identification was based on retention time, accurate measured mass, isotopic pattern and presence of specific fragments. For each substance, we set a calibration range encompassing infra-therapeutic, therapeutic, supra-therapeutic and toxic concentrations in order to generate semi-quantitative result. For 65% of the components, the limit of detection was below 5 ng/mL. The validation process showed the approach to be selective, sensitive, accurate and precise.
Conclusion: The method has been accredited by COFRAC (French Accreditation Committee) according to the ISO 15189 standard. Applicability was successfully tested by analyzing authentic serum, urine and whole blood samples.
Keywords: Clinical toxicology; High resolution mass spectrometry; LC–MS; Orbitrap; Toxicological screening; Turbulent flow chromatography.
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