Page 168 - CRFTApplication Compendium_090613

2 Direct Analysis using Paper-Spray Mass Spectrometry: Method Development for the Rapid Screening of Drugs of Abuse for Forensic Toxicology
O iverv ew
Purpose: Method development for the rapid screening of drugs of abuse in forensic
toxicology using paper spray mass spectrometry.
Methods: Bovine blood spiked with common drugs of abuse and analyzed as dried
FIGURE 1. Prototype paper sp
showing, clockwise from top l
dispensing solvent to the sa
and DBS-spotted paper casse
blood spots by paper spray ionization/Orbitrap mass spectrometry. Accurate mass full
MS and All Ion Fragmentation experiments for the identification and confirmation of
drugs from dried blood spot samples. Thermo Scientific™ TraceFinder™ 3.0 software
for data analysis.
Results: Able to identify six drugs of abuse tested down to 100 ng/mL from dried blood
spots. Limit of detection on single drug analysis to 10 ng/mL from dried blood spots.
Paper spray is easy to use, requires no sample preparation and no prior
chromatography, making for a quick technique with the potential to identify compounds
in seconds. The Thermo Scientific™ Exactive Plus system is ideally suited for coupling
to paper spray ionization.
Introduction
Paper spray is a direct ionization technique that simplifies the mass spectrometric
analysis of dried blood spots (DBS). Paper-spray technology is therefore attractive for
forensic toxicology screening for drugs of abuse. The sample collection and storage of
DBS in a simple paper cassette make shipment of samples to the forensic toxicology
lab safe and convenient. Both qualitative and quantitative analysis of small molecules
from complex matrices such as blood or other biological fluids is possible without time
consuming sample preparation and chromatography.
Single-component quantitation of DBS samples with paper-spray MS is fairly well
established. While previous work used a Thermo Scientific triple quadrupole mass
spectrometer and monitored specific MS/MS transitions, full-MS instruments with
Thermo Scientific™ Orbitrap™ analyzers are ideally suited as rapid screening tools.
Orbitrap analyzers provide high resolution accurate mass (HR/AM) full MS spectra for,
high confidence identification, allow for unlimited number of analytes in the method and
retrospective data analysis.
In this work, the ability of paper spray coupled to a very sensitive and fast Orbitrap
analyzer is explored for its potential as a forensic toxicology screening tool
FIGURE 2a. MS spectra for the
ion of amitriptyline at various
.
Methods
Sample Preparation
• Mixtures of drugs (Cerilliant TX) were spiked in blood (bovine blood Lampire
concentrations from DBS sam
Acquired at 70,000 resolving p
Mass accuracy 2-3 pp
, ,
Biologicals, New Jersey) stabilized with K2-EDTA.
• Blood sample integrity maintained by not exceeding 5% of solvent in blood (v/v).
• Single drug quantitation used a deuterated analog (500 ng/mL) as internal standard.
• Twelve microliters of spiked blood sample were loaded to paper cartridges, allowed 100
0
50
100 278.1911
278.1910
5000 ng/mL
to dry for two hours at room temperature and loaded into stackers that hold up to 40
cassettes.
• Solvent is automatically dispensed to the DBS before analysis and an applied high
voltage (3-5 kV) induces electrospray from the sharp tip of the paper (Figure 1).
• The extraction solvent used in this work is 95/5 (v/v) methanol/water at pH 4 5 0
50
100
0
50
278.1910
1000 ng/mL
500 ng/mL
. .
Mass Spectrometry
• The paper-spray source was coupled to a Thermo Scientific Exactive Plus benchtop
Orbitrap mass spectrometer.
The E acti e Pl s™ instr ment as operated at ario s resol ing po er settings
100
0
50
100 278.1909
278.1910
250 ng/mL
100 ng/mL • x v u u w v u v w ,
from 17,500 to 140,000 (FWHM at m/z 200) and in positive ionization MS mode.
• An automated experiment for drug screening consisted of 30 sec data collection,
switching back between full scan and All Ion Fragmentation (AIF) experiments.
• For screening, the MS Full scan data was acquired at 70,000 resolving power and 0
50
100
0
50
27
278.1909
27
278 1911
50 ng/mL
the AIF at 17,500 resolving power with a collision energy of 43 eV.
• All data acquisition used Xcalibur™ sequences and contact closure trigger from the
paper spray.
Data Analysis 50
100
0
50
100 .
27
278.1909
27
25 ng/mL
10 ng/mL
• QualBrowser and QuanBrowser software from the Xcalibur platform were used for
viewing and single compound quantitative analysis, respectively. TraceFinder™ 3.0
software was used for the automated identification and confirmation in the targeted
screening of drugs.
• Potential mass fragments were generated using Thermo Scientific™ MassFrontier™
278.15 278.20
m/z
0
7.0 software.