Akademik Veri Yönetim Sistemi
49.FEBS CONGRESS, İstanbul, Türkiye, 5 - 09 Temmuz 2025, ss.1-2, (Özet Bildiri)
High methamphetamine concentration interferes with amphetamine on LCMS/MS: Internal standard and product ion signal suppression
Introduction Chromatographic techniques are confirmatory for illicit drug tests; however they can also be prone to interferences. Methamphetamine accounts for 37% of all addictionrelated admissions in Türkiye, making it the most prevalent drug in emergency cases; those mostly have very high blood or urine concentration. In this report we detail interference from high methamphetamine concentration in an LCMS/MS assay. Materials and methods Ten urine samples were selected with methamphetamine concentrations ranging from 22,887 to 56,263 ng/mL, exhibiting amphetamined5 suppression, poor peak shape and an amphetamine peak characterized by the presence of the quantifier ion (136.1 > 119.0), but absence of the qualifier ion (136.1 > 91.0). Sample preparation was performed using the “dilute and shoot” technique on an Agilent 6475 LC/MSMS system, in positive MRM and electrospray ionization mode. Methamphetamined5 and amphetamined5 were employed as internal standards. Each sample was 10 to 100 for diluted using blank urine and subsequently reanalyzed. Quantitative analysis was performed using a sevenpoint calibration curve ranging from 0 to 1000 ng/mL. Qualifier ion and internal standard peak areas, and analyte concentrations were compared before and after dilution. Results and Conclusion While the amphetamine qualifier ions were not detected prior to dilution, both quantifier and qualifier ions became detectable after dilution. Additionally, the peak shapes and response of amphetamined5 aligned with those of the calibrators. Before dilution, the samples would have been interpreted as positive for methamphetamine but falsely negative for amphetamine. However, following dilution, the results were evaluated as positive for both methamphetamine and amphetamine, and quantification was made possible due to the correction of the amphetamined5 internal standard response. Awareness and management of such interferences are critical for accurate toxicological interpretation.