Page 70 - Clinical-Medical Solution for Clinical Chemistry

Quantitative Multi Target Screening (MTS) using liquid
chromatography-tandem mass spectrometry with MS/MS library
based identi cation for forensic toxicology

Introduction

Multi Target Screening (MTS) has been applied to using certi ed reference materials and included
systemic toxicological analysis to reduce false positive and electrospray spectral data from over 1200 compounds
negative reporting using MS/MS spectral library based relevant to clinical and forensic toxicology in both positive
identi cation. MTS methods uses threshold triggered and negative ion modes. The MTS approach was applied
multiple reaction monitoring (MRM) and MS/MS product to screening whole blood samples at three concentration
ion scans at three collision energies to con rm the levels to evaluate screening at therapeutic, overdose and
compound identi cation based on mass toxic concentrations.
spectral library searching. The MS/MS library was created

Methods and Materials

MTS methods were developed to screen whole blood effects. Data acquisition parameters were set to a single
spiked with a range of commonly observed compounds MRM per compound with threshold triggered MS/MS at 3
including antidepressant compounds, anxiolytic drugs, collision energies (10, 35, 55V) enabling con rmation of
analgesics and antipsychotic agents. Samples were parent ion (low) and fragment ions at medium and high
prepared by QuEChERS method with inclusion of ten CE voltages. Library searching was performed on all CE
internal standard compounds to normalise sample matrix spectral data in addition to a merged-CE spectrum.

Table 1. LC-MS/MS data acquisition conditions. The method included full scan and MRM data acquisition in both positive and negative ion mode.
10 internal standard compounds were also included in the method.

Liquid chromatography Mass spectrometry
UHPLC : Nexera LC system LC-MS/MS : LCMS-8060
Analytical column : Restek Raptor Biphenyl 2.7 µm 100 x 2.1 mm Ionisation mode : Heated ESI
Column temp. : 50°C Scan speed : 30,000 u/sec
Injection cycle : 5 µL injection volume Polarity switching time : 5 msec
Flow rate : 0.3 mL/min MRM Dwell time : 5 msec
Solvent A : Water + 2mM ammonium formate + 0.002% formic acid Pause time : 3 msec
Solvent B : Methanol + 2mM ammonium formate + 0.002% formic acid Interface temp. : 300°C
Binary Gradient : Heating block : 400°C
Time (mins) %B
Desolvation line : 250°C
1.00 5
Heating gas : 10 L/min
2.00 40 Drying gas : 10 L/min
10.50 100 Nebulising gas : 3 L/min
13.00 100 CID gas pressure : 250kPa
Interface voltage : 4 kV
13.01 5
17.00 Stop
11-14.2 0.5 mL/min

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