Comparison of Fragmentation Techniques for the Structural Characterization of Singly Charged Agrochemicals

Abstract

Investigating the structure of active ingredients, such as agrochemicals and their associated metabolites, is a crucial requisite in the discovery and development of these molecules. In this study, structural characterization by electron-induced dissociation (EID) was compared to collisionally activated dissociation (CAD) on a series of agrochemicals. EID fragmentation produced a greater variety of fragment ions and complementary ion pairs leading to more complete functional group characterization compared to CAD. The results obtained displayed many more cross-ring fragmentation of the pyrimidine ring compared to the pyridine ring. Compounds that consisted of one aromatic heterocyclic moiety (azoxystrobin, fluazifop acid, fluazifop-p-butyl, and pirimiphos-methyl) displayed cross-ring fragmentation while compounds with only aromatic hydrocarbon rings (fenpropidin and S-metolachlor) displayed no cross-ring fragmentation. The advantages of high-resolution accurate mass spectrometry (HRAM MS) are shown with the majority of assignments at ppb range error values and the ability to differentiate ions with the same nominal mass but different elemental composition. This highlights the potential for HRAM MS and EID to be used as a tool for structural characterization of small molecules with a wide variety of functional groups and structural motifs.

Advantages of Two-Dimensional Electron-Induced Dissociation and Infrared Multiphoton Dissociation Mass Spectrometry for the Analysis of Agrochemicals

“…The absolute average error obtained for this molecule was 0.289 ppm. The results obtained from the 2D-EID-MS experiment are comparable to the 1D-EID tandem MS results achieved in a previous study …”

“…The results obtained from the 2D-EID-MS experiment are comparable to the 1D-EID tandem MS results achieved in a previous study. 37 Internal Calibration of 2D. The pirimiphos-methyl fragmentation line was used to internally calibrate the 2DMS spectrum, resulting in spectrum-wide subppm accuracy.…”

Combining Ultraviolet Photodissociation and Two-Dimensional Mass Spectrometry: A Contemporary Approach for Characterizing Singly Charged Agrochemicals

“…The individual spectra were internally calibrated, using the product ions of these species labeled in the SI, to achieve sub-ppm accuracy. Elemental compositions, and thus cleavages, were assigned by the same procedure described previously …”

Advanced tandem mass spectrometry in metabolomics and lipidomics—methods and applications

“…These proof-of-concept experiments demonstrated that EID and CID fragment ions can differ and that the additional EID fragment ions facilitate analyte identifications. In a recent study by Marzullo et al, the benefits of EID for metabolite structure elucidation for a set of seven agrochemicals were impressively showcased [42]. A representative example comparing CID (or collision-activated dissociation, CAD) and EID mass spectra of protonated azoxystrobin, a commonly used fungicide, is shown in Fig.…”

“…With the aid of nanosecond pulsed solid-state and gas-phase laser systems, which offer energies up to 150 J/pulse and often operate at 157 nm, 193 nm, 213 nm, 248 nm, 266 nm, 337 nm, 351 nm, and 355 nm with repetition rates between 10 and 5000 Hz, many metabolite and lipid ions are readily activated in the gas phase. In the IR region especially O-H, N-H, C=O, and P-O, valence [42], copyright 2020 American Chemical Society. (ii) EID-MS 2 of protonated (blue) PC 16:1(9Z)/16:1(9Z) and (purple) PC 16:1(9E)/16:1(9E).…”