APHL 2018 Annual Meeting Poster Abstracts
Single-Injection Screening of 664 Forensic Toxicology
Compounds Using an Innovative Benchtop High Resolution
Mass Spectrometer
O. Cabrices , C. Schwarz , X. He , H. McCall , L. Baker , A. Wange , A.
Taylor 2 ; 1 SCIEX, Redwood City, CA, 2 SCIEX Canada, Concord, ON, Canada
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Presenter: Oscar Cabrices, PhD, SCIEX, Redwood City, CA, Phone:
908.472.4797, Email: [email protected]
P. Winkler 1 , K.C. Hyland 1 , S. Krepich 2 ; 1 SCIEX, Redwood City, CA,
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Phenomenex, Torrance, CA
With the US EPA ruling to continue to allow the application of
Dicamba to important agricultural crops, interest in this and related
herbicide compounds and their degradation products has increased
in the US. Dicamba, 2,4-D and other herbicides comprise a large
portion of the widely applied chemical herbicide compounds.
Quantitative determination of these and other related acid
herbicides and metabolites to low levels in relevant environmental
matrices represents a crucial analytical need in the environmental
and agricultural testing spaces. The ability to effectively and reliably
perform quantitative analysis in complex extracts of soil and plant
tissues by LC-MS/MS without the need for chemical derivatization
is demonstrated. A SCIEX QTRAP 6500+ system is employed for
its sensitivity and robustness. Isotopically labelled version of a
subset of the target analytes are employed as internal standards
for achieving the highest quality quantitation data in complex soil
and plant extracts. Quantitative method performance and recovery
values were investigated and reported. Chromatographic separation
of these highly polar, low molecular species was achieved using a
Phenomenex Kinetex F5 column. Excellent analyte retention and
peak quality is demonstrated using this relatively novel stationary
phase. Preliminary sensitivity data for the acid herbicides suite
using the QTRAP 6500+ system demonstrates that achievement
of limits of quantitation (LOQs) in the parts per trillion range is
possible. Reproducibility and robustness over multiple injections is
reported.
Presenter: Paul Winkler, SCIEX, Redwood City, CA,
Email: [email protected]
Microcystins in Drinking Water Utilizing High Resolution
Mass Spectrometry
K. Hyland, SCIEX, Redwood City, CA
High resolution-accurate mass (HRAM) mass spectrometric
analyses allow environmental screening and quantitation methods
to be extremely confident in the identification of residues and
contaminants. Quantitative workflows typically involving a targeted
list of MRM transitions for acquisition can be expanded to include
suspect and nontarget screening and utilization of both accurate
mass and spectral database searching to achieve the most
useful information. Paramount to the success of these types of
applications is the ability to identify residues in environmental
samples, confirm such identification using multiple attributes and
to quantify an identified target. Workflows are presented which
demonstrate mult iple approaches for using MRMHR to achieve
quantitative and qualitative analyses of microcystins in drinking
water. Additional workflow showing the parallel application of
SWATH data independent MSMS acquisition is also outlined and
the advantages and challenges of these approaches are directly
compared. The capacity to achieve high resolution mass spectral
data for environmental screening, monitoring and measurement
of trace level organic contaminants combined with seamless data
processing for multiple workflows on a single platform is presented
as an advantage to the environmental analyst interested in multiple
facets of sample analysis.
Presenter: Paul Winkler, SCIEX, Redwood City, CA,
Email: [email protected]
PublicHealthLabs
@APHL
APHL.org
Summer 2018 LAB MATTERS
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Quadrupole Time-of-flight mass spectrometry (QTOF-MS) provides
high-resolution, accurate-mass data for full-scan information of
both precursor ion and all product ions. This is an ideal approach
for forensic toxicology screening where unknown compounds in
complex biological samples must be identified from information-
rich data sets. Herein, we present a single-injection method for
screening 664 most up-to-date forensic compounds using an
innovative benchtop QTOF mass spectrometer. The obtained data
provided both structural information and retention times to enhance
identification accuracy, especially for structurally similar isomers.
Sample preparation procedures for urine and whole blood samples
and library-search settings are described for confident unknown
substance identification within an efficient, all-in-one workflow.
Urine and whole blood samples were spiked with stock standard
mixtures and used to determine the retention time of the 664
compounds. Urine samples were diluted with mobile phase and
analyzed; whole blood samples, were extracted by using protein
precipitation and centrifugation; supernatant was evaporated
and reconstituted in mobile phase for analysis. Analytes were
chromatographically separated using a Phenomenex Kinetex phenyl-
hexyl column. Mobile Phase was ammonium formate in water and
formic acid in methanol, 600 µL/min flow rate. The QTOF-MS was
operated in positive electrospray mode with information dependent
acquisition MS/MS methods. Samples were evaluated against
a list of parameters containing the names, molecular formulas
and retention times for all compounds. Compound retention time
(RT) was a critical element for accurate identification of each
forensic analyte using this screening method, the following RT
reproducibility tests were conducted for each compound to evaluate
the robustness of the LC condition in this method: (1) reproducibility
on 3 separate columns; (2) the inter-day (n=3) reproducibility; (3)
the reproducibility in neat versus matrix samples. The reproducibility
tests indicated that the RTs generated from the optimized LC
conditions are consistent and reproducible. RTs measured on three
separated analytical columns all have %CVs of less than 5% for
each of the 664 compounds. RT inter-day reproducibility (tested on
80 compounds) resulted in %CVs less than 5% over 3 days. Lastly,
RT variability in human whole blood and urine samples (tested
on 80 compounds) indicated that the %CV for 3 individual lots is
less than 5%. The retention time determined by the optimized LC
condition combined with high-resolution mass spectrometry and
MS/MS spectra, enabled accurate compound identification across
the workflow. Retrospective analysis was also performed on the
acquired data sets to screen for new compounds without having
to re-inject samples, allowing data sets to be re-processed as new
forensic targets were discovered.
Quantitative Analysis of Dicamba and Related Acid
Herbicides and Metabolites