Screening for Unknown Toxins in Biological Matrices Using Ion Trap

Accessing technology to determine structural elucidation affordably is increasingly important in the field of toxicology. Being able to add new compounds is a critical component of toxicology screening analyses. But how can compounds be added quickly without impacting results in lower volume forensic toxicology laboratories?

Overview: Some common techniques for performing toxicology screening analyses include automated immunoassaysgas chromatography-mass spectrometry (GC-MS), and high pressure liquid chromatography-diode array detector (HPLC-DAD). However, these techniques are unable to identify all the toxic compounds potentially present in a urine or plasma sample. Using liquid chromatography-mass spectrometry (LC-MS) for toxicology screening provides several benefits, such as an easy sample preparation procedure and fewer limitations based on compound volatility and thermal stability.

Method: A Thermo Scientific™ LXQ Ion Trap™ mass spectrometer is used to identify unknown compounds in human urine and plasma samples. Samples are analyzed using electrospray ionization (ESI), and HPLC separation is performed with a Thermo Scientific™ Accela™ pump using a Thermo Scientific™ Hypersil™ Gold PFP column. An MS/MS spectral library of 275 drugs and toxic compounds is created, and Thermo Scientific™ ToxID™ software is used to identify compounds present in the sample based on MS/MS spectra and retention times.

Table 1. Thirteen-minute LC method

Time (minutes) %A %B
0 95 5
0.5 95 5
5.5 5 95
8.5 5 95
8.6 5 95
13 95 5

Results: This LC-MS/MS workflow allows the user to quickly and easily add new analytes to the screening method, with new compounds typically able to be added in less than 1 hour. With ToxID software performing automatic data analysis and reporting, the need for manual data interpretation is eliminated, which increases confidence in compound identification. When compared to other screening methods, the LC-MS/MS screening methodology identifies more analytes.

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