Characterization of industrial alkylpolyphosphonates by infusion electrospray ionization‐ion trap mass spectrometry with identification of the impurities by tandem capillary zone electrophoresis

Abstract

Technical grade diethylene-triaminepentakis(methylenephosphonic acid) (I), dihexamethylene-triaminepentakis(methylenephosphonic acid) (II), ethylene-diaminetetrakis(methylenephosphonic acid) (III), hexamethylene-diaminetetrakis(methylenephosphonic acid) (IV), amino-tris(methylenephosphonic acid) (V), hydroxyethyl-aminobis(methylenephosphonic acid) (VI), 1-hydroxyethylidene-1,1-diphosphonic acid (VII), and 2-phosphonobutane-1,2,4-tricarboxylic acid (VIII) were characterized by ion trap mass spectrometry with electrospray ionization (ESI-ITMS). Using the negative ion mode and acid and alkaline media, peak series corresponding to the nominal compounds and to impurities with a lower number of phosphonate groups were distinguished in I-V. Each series was constituted by [M - nH + (n - 1)Na](-) peaks and peaks produced from them by losses of water, H(3)PO(3)(or water plus HPO(2)), and combined losses. For each [M - nH + (n - 1)Na](-) peak, the number of losses coincided with the number of phosphonate groups not bound to sodium ions minus one (the group bearing the charge). Owing to the hydroxyethyl group, the spectrum of VI was dominated by the formation of intermolecular esters, with both losses and gains of water according to [nM - H +/- mH(2)O](-). A series of [M - nH + (n - 1)Na](-) peaks were observed for VII and VIII, showing in the latter case that the carboxylate groups may also form adducts with sodium ions. Losses of water and H(3)PO(3)were observed in VII, whereas losses of water, CO(2), and HPO(3) were seen in VIII. The reaction pathways leading to the production of the observed ions are described. The nominal compounds and the impurities were also separated and identified by capillary electrophoresis with ESI-ITMS detection.

Rapid characterization of alkylpolyphosphonates by CZE with indirect photometric and mass spectrometric detection

“…In a previous study, impurities of products I-V having the same hydrocarbon skeleton as the corresponding nominal compound, but with one or two -PO(OH) 2 groups substituted by protons, were found [22]. Impurities lacking one or two -CH 2 -PO(OH) 2 groups, and simultaneously lacking a -PO(OH) 2 group and a -CH 2 -PO(OH) 2 group, were also identified in the present work (see Tables 1-3).…”

“…The identification procedures are next discussed. First, with the exception of VI, the infusion spectra of the APPs showed a characteristic peak pattern [22]. For each compound or group of isomers, the more intense peaks corresponded to a [M 2 nH 1 (n-1)Na] 2 series, where n ranged from 1 up to the number of -PO(OH) 2 groups.…”

“…2 , p varying from 1 to 4, and m standing for both losses and gains of water [22]. Within the first group of peaks (p = 1), the large peak at m/z 230 was interpreted as due to dehydration of the [M 2 H] 2 ion of VI-C4N1P2(OH) in the mass spectrometer.…”

“…In a previous study, the infusion ESI-MS of eight common industrial APPs were described [22]. Compounds having the same hydrocarbon skeleton as the nominal compounds, but with one or two -PO(OH) 2 groups substituted by protons, were found.…”

Study of bisphosphonates by matrix‐assisted laser desorption/ionization mass spectrometry – influence of alkali atoms on fragmentation patterns

“…Electrospray ionization mass spectrometry (ESI‐MS) is the most used technique for the study of non‐volatile small compounds and HMBPs have been exclusively analyzed in negative ion mode 8–11. Since the first MS fragmentation study12 only few mass spectrometric studies have been carried out on HMBPs.…”