前言：

　　Screening of biological samples for drugs of abuse and other toxic compounds is one of the main issues in forensic toxicology. The challenge is to provide rapid and accurate results despite the large number of targeted molecules and the complexity of biological matrices.

　　Here we present the workflow and results obtained by using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) timed selected reaction monitoring (T-SRM) method utilizing a triple stage quadrupole mass spectrometer. In a T-SRM experiment, the method is set to look for specific transitions only during the expected retention-time window. This increases the number of SRM transitions that can be monitored in a single experiment. It also increases the dwell time and duty cycle for monitoring individual compounds per experiment. Then, quantitationenhanced data dependent (QED) MS/MS scan functions are used to trigger data dependent full scan MS/MS spectra from SRM transitions. When a particular SRM transition reaches a predefined intensity threshold, the instrument automatically triggers QED-MS/MS, using the reverse energy ramp (RER) scan function to increase the product ion sensitivity (Figure 1). Dynamic exclusion settings allow the maximum number of MS/MS collected for each compound to be specified, thus giving the ability to collect MS2 spectra of coeluting molecules.

仪器：

Thermo Scientific TSQ Quantum mass spectrometer

结论：

　　The TSQ Quantum Access MAX™ with T-SRM and QED-RER acquisition mode was used to screen toxic compounds and their metabolites in urine. This screening approach provides rapid sample preparation, ease-of-use, sensitivity, specificity, and a low cost per sample analysis for forensic toxicology laboratories.