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Direct Analysis using Paper-Spray Mass Spectrometry: Method Development for the Rapid Screening of Drugs of Abuse for Forensic Toxicology
Overview
Purpose:
Method development for the rapid and semi-quantitative 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 blood
spots by paper spray ionization/Orbitrap mass spectrometry. High resolution and accurate
FIGURE 1. Prototype pap
clockwise from top left: p
solvent to the sample, pa
spotted paper cassette el
mass used in full MS, MS
2
and All Ion Fragmentation experiments for the identification and
confirmation of drugs from dried blood spot samples. Thermo Scientific™ TraceFinder™
3.0 software used for data analysis.
Results:
Able to identify six drugs of abuse from dried blood spots at a 100 ng/mL level
with outstanding signal to noise Limit of detection from dried blood spots with this
.
technique is 1-10 ng/mL, compound dependent. 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™ Orbitrap™ Exactive™
family of mass spectrometers are 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
f
f
f
simple paper cassette make shipment o samples to the orensic toxicology lab sa e 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.
Quantitation of DBS samples with paper spray MS is fairly well established even though a
-
commercial product is not yet available (1). While previous work used a Thermo Scientific
triple quadrupole mass spectrometer and monitored specific MS/MS transitions, full-MS
instruments with Orbitrap analyzers are ideally suited as rapid screening tools. Orbitrap
analyzers provide high resolution, accurate mass (HR/AM) analysis for high confidence
identification allow for unlimited number of analytes in the method and retrospective data
,
analysis is possible because a full MS spectrum is recorded in addition to All Ion
Fragmentation (AIF) or Data Dependent (DD) MS/MS.
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.
Methods
Sample Preparation
Mixtures of drugs (Cerilliant TX) were spiked in blood (bovine blood Lampire
FIGURE 2. Full scan MS
140,000 (FWHM at
m/z
20
due to matrix interferenc
below Resolving power
•
,
,
Biologicals, New Jersey) stabilized with K2-EDTA. Blood sample integrity maintained by
not exceeding 5% of solvent in blood (v/v).
• Twelve microliters of spiked blood sample were loaded to paper cartridges, dried under a
nitrogen gas flow for 20 min and loaded into stackers that hold up to 40 cassettes.
.
The [M+H]
+
ion is highlig
• 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 with 100 ppm acetic
acid (pH 4.5).
60
80
100 136.0738
amphetamine
17 500
RP
Mass Spectrometry
• The paper-spray source was coupled to either a Thermo Scientific™ Exactive Plus™ or
a Thermo Scientific™ Q Exactive™ Orbitrap mass spectrometer.
• An automated experiment for drug screening consisted of 30 sec data collection,
switching between full scan and AIF experiments (Exactive Plus MS) or full scan and
40
60
80
100
tive Abundance
0
20
40
136.1130
136.0738
136.1127
136.1055
,
35,000
Data Dependent Higher Collision Dissociation (HCD) MS/MS (Q Exactive MS).
• For maximum specificity and sensitivity, both full scan and fragmentation data were
acquired at 140,000 resolving power (FWHM at m/z 200). Normalized collision energy
was 40 eV.
0
20
40
60
80
100
0
20
Rela
136.1127
136.0739
136.1057
70,000
• All data acquisition used the Thermo Scientific™ Xcalibur™ sequences and contact
closure trigger from the paper spray source.
Data Analysis
• Thermo Scientific™ QualBrowser™ software from the Xcalibur platform was used for
136.10
0
20
40
60
80
100
136.1127
136.0739
136.1056
136.0845
140,000
spectra visualization. TraceFinder 3.0 software was used for the automated identification
and confirmation in the targeted screening of drugs.
m/z