Liquid Chromatography, In Combination with a Quadrupole Time-of-Flight Instrument, with Sequential Window Acquisition of All Theoretical Fragment-Ion Spectra Acquisition: Validated Quantification of 39 Antidepressants in Whole Blood As Part of a Simultaneous Screening and Quantification Procedure

Abstract

Sequential window acquisition of all theoretical fragment ion spectra (SWATH) is a data independent acquisition (DIA) method for very fast scanning quadrupole time-of-flight (QTOF) instruments. SWATH repeatedly cycles through 28 consecutive 20 Da precursor isolation windows detecting all precursor ions and fragments MS ALL like and yet fast enough to generate more than 10 data points over the chromatographic peak. It was already shown in previous publications that SWATH, despite its wide Q1 windows, allows the identification of different substances and that SWATH has a higher identification rate than data dependent acquisition approaches. The aim of this study was a proof of concept study whether these same data sets can also enable validated quantification according to international guidelines, exemplified for 39 antidepressants. The validation included recovery, matrix effects, process efficiency, ion suppression, and enhancement of coeluting ions, selectivity, accuracy, precision, and stability. The method using SWATH acquisition proved to be selective, sensitive, accurate, and precise enough for 33 out of the 39 antidepressants. The applicability of SWATH for screening and validated quantification in the same run was successfully tested with authentic whole blood samples containing different antidepressants and other drugs thus proving the QUAL/QUAN abilities of SWATH. In an additional systematic investigation, it could be shown that calibration curves injected a few days after or before the actual sample can be used for quantification with acceptable accuracy.

High-resolution mass spectrometry in toxicology: current status and future perspectives

“…They concluded that non-targeted screening procedures (general unknown screening) could easily be performed by HRMS (Kinyua et al 2015;Lung et al 2016), although most authors still develop targeted screening procedures. They also discussed the advantage of so-called sequential window acquisition of all theoretical fragment ion spectra (SWATH) for very fast scanning (QTOF) instruments as a promising option for non-targeted HRMS screening in clinical and forensic toxicology (Roemmelt et al 2014;Scheidweiler et al 2015;Roemmelt et al 2015). Castaneto et al (2015) and Znakeziona et al (2015) reviewed at the same time papers on the metabolism and detection of synthetic cannabinoids in various body samples with more or less discussion on the impact of HRMS.…”

“…Qualitative procedures using QTOF instruments, SWATH acquisition, and low collision energy scan followed by the stepwise acquisition of high collision energy scans using a specific quadrupole isolation range were published by Arnhardt (Arnhard et al 2015), Rommelt (Roemmelt et al 2014(Roemmelt et al , 2015, and Scheidweiler (Scheidweiler et al 2015). Arnhard et al (2015) used 21 m/z isolation windows to assess the performance of identifying compounds in samples typically encountered in forensic casework.…”

“…However, one could expect a higher need of instrument maintenance associated with such high sample loads. Roemmelt et al (2014Roemmelt et al ( , 2015 published two papers on the use of SWATH in screening for drugs in human samples. In the first study, they systematically investigated its suitability for toxicological analysis using windows of 20-35 m/z for stepwise fragmentation with a focus on the quality of SWATH-generated mass spectra.…”

“…As already discussed above, some screening methods allowed simultaneous quantification such as that by Roemmelt et al (2015). Gous et al (2014) used HRMS to quantify the oral anticoagulants apixaban, dabigatran, edoxaban, and rivaroxaban.…”

Nested data independent MS/MS acquisition

“…Data independent acquisition [1,2] has received a great deal of attention in the field of proteomics [3][4][5], metabolomics [6], and, more recently, clinical forensic [7][8][9] residue and environmental analysis. The identification, or at least the tentative identification, of compounds requires the availability of MS/ MS data [10].…”