Identification tree based on fragmentation rules for structure elucidation of organophosphorus esters by electrospray mass spectrometry

Abstract

Organophosphorus compounds have played important roles as pesticides, chemical warfare agents and extractors of radioactive material. Structural elucidation of phosphonates poses a particular challenge because their initial forms can be hydrolyzed, thus, degradation products may predominate in samples acquired in the field. The analysis of non-volatile organophosphorus compounds and their degradation products is possible using electrospray tandem mass spectrometry ESI-MS/MS. Here, we present a generic strategy that allows the unambiguous identification of substituents for two families of organophosphorus compounds: the phosphonates and phosphates. General fragmentation rules were deduced based on the study of decomposition pathways of 55 organophosphorus esters, including examples found in the literature. Multistage MS (MS(n)) experiments at high resolution in a hybrid mass spectrometer provide accurate mass measurements, whereas collision-induced dissociation experiments in a triple quadrupole give access to small fragment ions. The creation of a specific nomenclature for each possible structure of organophosphorus compound, depending on the alkyl side chain linked to the oxygen, was achieved by applying these fragmentation rules. This led to the creation of an 'identification tree' based upon the unique consecutive decomposition pathways uncovered for each individual compound. Hence, seven structural motifs were created that orient an unequivocal identification using the 'identification tree'. Despite the similar structures of the ensemble of phosphate and phosphonate esters, distinct identifications based upon characteristic neutral losses and diagnostic fragment ions were possible in all cases.

Specificity enhancement by electrospray ionization multistage mass spectrometry – a valuable tool for differentiation and identification of ‘V’‐type chemical warfare agents

“…This generalization is based on ESI/MS/MS fragmentation rules previously derived for organophosphorus esters and similar derivatives; when up to a C 8 alkyl group was attached to an oxygen, an alkene cleavage was observed . This observation is in accordance with other published results both in EI and ESI …”

Qualitative and quantitative investigation of organophosphates in an electrochemically and thermally treated lithium hexafluorophosphate-based lithium ion battery electrolyte by a developed liquid chromatography-tandem quadrupole mass spectrometry method

“…The mass spectra of TMP and TEP investigated by LC-MS/MS are known in literature [31][32][33]35 and are in agreement with the presented results. Furthermore, the interpretation of the mass spectra is highly facilitated with fragmentation rules for non-ionic OPs, which were systematized by Weissberg et al 38 and Schwarzenberg et al 39 A neutral loss of ethene (m/z 28) was observed by DEFP, TEP, DMEP, DEMP, MEDEP and EEDEP. Furthermore, diethylated or triethylated compounds such as DEFP, TEP and DEMP have a multiple loss of ethene in agreement to the rules.…”

Further Insights into Structural Diversity of Phosphorus-Based Decomposition Products in Lithium Ion Battery Electrolytes via Liquid Chromatographic Techniques Hyphenated to Ion Trap-Time-of-Flight Mass Spectrometry

“…In the field of LIB electrolyte investigations, classic reversed-phase (RP) chromatography has been reported. − Nevertheless, the HPLC allows one to separate nonacidic molecules with hydrophobic stationary phases as well as acidic molecules by changing the separation mode to hydrophilic interaction liquid chromatography (HILIC). , HILIC enables the conversion of the chromatographic order of RP separation and allows the comprehensive investigation of O­(F)­Ps by using a single instrument setup with two different stationary phases. For structure elucidation of decomposition products in LIB electrolytes, not only is an effective separation required but also good mass accuracy by high resolution mass spectrometry and fragmentation information . Thus, a hybrid ion trap-time-of-flight-mass spectrometer (IT-TOF-MS) is the method of choice to generate high certainty in structure elucidation without analytical standards.…”

“…For structure elucidation of decomposition products in LIB electrolytes, not only is an effective separation required but also good mass accuracy by high resolution mass spectrometry and fragmentation information. 56 Thus, a hybrid ion trap-timeof-flight-mass spectrometer (IT-TOF-MS) is the method of choice to generate high certainty in structure elucidation without analytical standards.…”