Lab Matters Summer 2018 - Page 53

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 1 1 1 1 1 1 Presenter: Oscar Cabrices, PhD, SCIEX, Redwood City, CA, Phone: 908.472.4797, Email: oscar.cabrices@sciex.com P. Winkler 1 , K.C. Hyland 1 , S. Krepich 2 ; 1 SCIEX, Redwood City, CA, 2 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: paul.winkler@sciex.com 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: paul.winkler@sciex.com PublicHealthLabs @APHL APHL.org Summer 2018 LAB MATTERS 51 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 ┬ÁL/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