Development of rapid methodologies for the isolation and quantitation of drug metabolites by differential mobility spectrometry – mass spectrometry

Abstract

Clinical and forensic toxicology laboratories are inundated with thousands of samples requiring lengthy chromatographic separations prior to mass spectrometry. Here, we employ differential mobility spectrometry (DMS) interfaced to nano-electrospray ionization-mass spectrometry to provide a rapid ion filtration technique for the separation of ions in gas phase media prior to mass spectral analysis on a DMS-integrated AB SCIEX API 3000 triple-quadrupole mass spectrometer. DMS is efficient at the rapid separation of ions under ambient conditions and provides many advantages when used as an ion filtration technique in tandem with mass spectrometry (MS) and MS/MS. Our studies evaluated DMS-MS/MS as a rapid, quantitative platform for the analysis of drug metabolites isolated from urine samples. In targeted applications, five metabolites of common drugs of abuse were effectively and rapidly separated using isopropanol and ethyl acetate as transport gas modifiers, eliminating the gas chromatography or liquid chromatography-based separations commonly employed in clinical and forensic toxicology laboratories. Calibration curves were prepared for the selected drug metabolites utilizing deuterated internal standards for quantitative purposes. The feasibility of separating and quantitating drug metabolites in a rapid fashion was evaluated by compensation voltage stepping followed by multiple reaction monitoring (MRM) detection. Rapid profiling of clinical and forensic toxicology samples could help to address an urgent need within the scientific community by developing high-throughput analytical methodologies, which could reduce significant case backlogs present within these laboratories.

Rapid and High-Throughput Detection and Quantitation of Radiation Biomarkers in Human and Nonhuman Primates by Differential Mobility Spectrometry-Mass Spectrometry

“…Gas modifiers were introduced to the curtain gas by a syringe pump and went through a 50°C heated metal tube connected to the curtain gas inlet so that the organic solvent was completely evaporated. The percentage of the gas modifier in the curtain gas was calculated by liquid delivery rate, liquid density, and the ideal gas law [23]. …”

“…Differential Mobility Spectrometry (DMS) in combination with MS (DMS-MS) is an area of considerable in-house activity and has proved effective for many applications, including peptide analysis, drugs of forensic interest [7, 23–25], and recently DNA damage biomarker analysis [26]. Here, we investigate DMS-MS as an alternative approach to LC-MS for select biodosimetry biomarkers analysis.…”

“…Here, we investigate DMS-MS as an alternative approach to LC-MS for select biodosimetry biomarkers analysis. DMS offers rapid gas phase separation/filtration prior to mass analysis and the advantages of this platform such as improved signal to noise (S/N) ratio, separation of closely related compounds and removal of background interferences, have been well demonstrated by a number of groups [7, 23, 26]. Moreover, improved selectivity, and hence, further improvement in S/N ratio, can be achieved via the addition of modifiers to the transport gas [27].…”

“…Since DMS can preselect ions before MS, it can function as a pre-filter and thus serves as an orthogonal separation technique to MS [28]. The ion filtration time in DMS is only milliseconds, and thus is no constraint on high-throughput analysis, which is only limited by the rate of sample delivery and sample transfer line clearance [23, 26]. A comparison of analysis times between LC-MS and DMS-MS is summarized in Table 1, showing a clear advantage of DMS-MS over LC-MS for targeted analysis.…”

Making Methods Rugged for Regulated Bioanalysis

“…They play a much larger role beyond proof-of-concept studies where population diversity greatly increases. Having a toolkit of approaches to recognize (accurate mass, MS 3 ) and resolve (LC, differential mobility, MRM) them is critical to keeping studies on track [39,40].…”