Mass Spectrometry & Spectroscopy
The Forensics 664 vMethod: Accurate and Specifi c Forensic Toxicology Screening
Author details: Phil Taylor, Global Marketing Manager, Food, Environmental and Forensic, Sciex Warrington, UK
As drug abuse continues to grow worldwide, the need for accurate and specifi c forensic toxicology screening increases. Mass spectrometry, specifi cally LC-MS/MS has become the preferred method for forensic drug screening and an ideal approach is quadrupole time-of-fl ight MS as it provides high-resolution, accurate-mass data for full-scan information of both precursor ion and all product ions. This article describes a method for forensic drug screening using the SCIEX X500R QTOF system, which generates data that offers more confi rmation criteria than nominal mass triple quad workfl ows, and reduces the risk of reporting false positives and false negatives that could compromise an investigation.
Introduction
An estimated 183,000 drug-related deaths occurred worldwide in 2012, according to the United Nations Offi ce on Drugs and Crime 2014 World Drug Report [1] and more than 300 million people (7% of the global population) used an illicit drug last year. These statistics clearly display a critical need for law enforcement agencies to undertake specifi c and accurate drug testing. Forensic toxicology screening identifi es drugs and their metabolites, chemicals, volatile substances, gases and metals in human tissues for law enforcement purposes. It relies on the identifi cation of unknown compounds from complex samples and information-rich data sets.
During recent years, mass spectrometry, and specifi cally LC-MS/MS has become the industry’s preferred method for forensic toxicology screening due to its sensitivity, selectivity and accuracy over conventional methods such as GC, GC-MS and UV detection.
An ideal approach is quadrupole time-of-fl ight mass spectrometry (QTOF-MS) as it provides high-resolution, accurate-mass data for full-scan information of both precursor ions and all product ions. An LC-MS/MS-based toxicological screening method has recently been developed that includes the retention times for 664 forensic compounds. When combined with high-resolution mass spectrometry (HRMS) and HR-MS/MS information, the retention time enables more accurate compound identifi cation and an enhanced ability to identify structurally similar isomers.
Figure 2. Representative search results obtained after using a targeted screening approach to identify compounds in urine samples.
This is the fi rst verifi ed method for forensic drug screening using the X500R QTOF system and data generated from this method offer more confi rmation criteria than nominal mass triple quad workfl ows. The unique high-resolution spectra deliver unrivalled confi dence in reporting the detected analyte. Cross-referencing the data with a forensic library gives added confi rmation and the method reduces the risk of reporting false positives and false negatives that could compromise an investigation.
Materials and Methods Sample preparation
Figure
1.The parameters used for the integration of hydromorphone.
The stock standard mixtures in neat solutions were diluted with methanol: water (20:80, v/v) to appropriate concentrations. These diluted solutions were used to determine the retention time of the 664 compounds using a SCIEX X500R QTOF system. Subsequently, the urine and whole blood samples were prepared to confi rm the retention times in matrix. For urine samples, stock standards solutions (10.0 µL) were added into human urine matrix (90.0 µL) and then diluted 10-folds with methanol:water (20:80, v/v). After centrifugation at 8,000 rpm for 5 min, the supernatant was used for LC-MS analysis. For whole blood
LAB ASIA - JANUARY/FEBRUARY 2018
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