Characterizing Multidevice Capillary Vibrating Sharp-Edge Spray Ionization for In-Droplet Hydrogen/Deuterium Exchange to Enhance Compound Identification

Abstract

Multidevice capillary vibrating sharp-edge spray ionization (cVSSI) source parameters have been examined to determine their effects on conducting in-droplet hydrogen/deuterium exchange (HDX) experiments. Control experiments using select compounds indicate that the observed differences in mass spectral isotopic distributions obtained upon initiation of HDX result primarily from solution-phase reactions as opposed to gas-phase exchange. Preliminary studies have determined that robust HDX can only be achieved with the application of same-polarity voltage to both the analyte and the deuterium oxide reagent (D 2 O) cVSSI devices. Additionally, a similar HDX reactivity dependence on the voltage applied to the D 2 O device for various analytes is observed. Analyte and reagent flow experiments show that, for the multidevice cVSSI setup employed, there is a nonlinear dependence on the D 2 O reagent flow rate; increasing the D 2 O reagent flow by 100% results in only an ∼10−20% increase in deuterium incorporation for this setup. Instantaneous (subsecond) response times have been demonstrated in the initiation or termination of HDX, which is achieved by turning on or off the reagent cVSSI device piezoelectric transducer. The ability to distinguish isomeric species by in-droplet HDX is presented. Finally, a demonstration of a three-component cVSSI device setup to perform multiple (successive or in combination) in-droplet chemistries to enhance compound ionization and identification is presented and a hypothetical metabolomics workflow consisting of successive multidevice activation is briefly discussed.

In-droplet hydrogen-deuterium exchange to examine non-canonical DNA structures

“…Monitoring such positioning is achieved using an internal standard (dT6) and monitoring its m/z-shifted isotopic distribution as the emitter The percent deuterium uptake (%D) for each analyte is determined using shifts in the weighted-average isotopic distributions of the analyte ions as described in detail previously. 39 Briefly, for 5 -24TTG ions, a m/z shift (1529.2 to 1530.7) in the weighted-average isotopic distribution is observed as shown in Figure 4C, D; this corresponds to an average deuterium uptake value of ~8.7. Similarly, for the same charge state for 23TAG the shift corresponds to an uptake value of ~15.7 (Figure 4E, F).…”

“…A fast and consistent droplet mixing/exchange strategy has been recently demonstrated using such a setup where the ability to distinguish small-molecule isomers was demonstrated. 39,40 Here the approach is extended to larger molecules; HDX is monitored for a number of single-strand, duplex, and Gquadruplex (containing two K + adducts) ions and the most intense, low charge-state species are utilized to compare exchange levels.…”

“…In the present study, rapid solution-phase HDX was facilitated using the novel ionization technique termed capillary vibrating sharp-edge spray ionization (cVSSI) 38,39 employing a dual spray emitter set up as shown in Figure 2. In this approach, one emitter is used to ionize the analyte DNA while the other is used to create a plume of D 2 O droplets.…”

Integration of capillary vibrating sharp-edge spray ionization as a nebulization device for ICP-MS

“…Since the development of cVSSI in 2019, several applications for mass spectrometry have been explored, including uses in droplet hydrogen/deuterium exchange, liquid chromatography, solid phase microextraction, and native biomolecule analysis. 28–32…”

Nanoflow Sheath Voltage-Free Interfacing of Capillary Electrophoresis and Mass Spectrometry for the Detection of Small Molecules

“…The introduction of acoustic waves to the liquid surface results in a plume of droplets that desolvate to produce gas phase ions suitable for MS analysis. Different designs couple the acoustic energy and liquid through the sharp edge, including the corner of a piece of glass for direct contact-based nebulization , or using a capillary attached to the piece of glass − with fluid through the capillary. Unlike traditional electrospray interfacing, VSSI is voltage-free ionization and does not utilize nebulizer gas.…”