Analysis of antioxidants in insulation cladding of copper wire: a comparison of different mass spectrometric techniques (ESI–IT, MALDI–RTOF and RTOF–SIMS)

Abstract

Commercial copper wire and its polymer insulation cladding was investigated for the presence of three synthetic antioxidants (ADK STAB AO412S, Irganox 1010 and Irganox MD 1024) by three different mass spectrometric techniques including electrospray ionization-ion trap-mass spectrometry (ESI-IT-MS), matrix-assisted laser desorption/ionization reflectron time-of-flight (TOF) mass spectrometry (MALDI-RTOF-MS) and reflectron TOF secondary ion mass spectrometry (RTOF-SIMS). The samples were analyzed either directly without any treatment (RTOF-SIMS) or after a simple liquid/liquid extraction step (ESI-IT-MS, MALDI-RTOF-MS and RTOF-SIMS). Direct analysis of the copper wire itself or of the insulation cladding by RTOF-SIMS allowed the detection of at least two of the three antioxidants but at rather low sensitivity as molecular radical cations and with fairly strong fragmentation (due to the highly energetic ion beam of the primary ion gun). ESI-IT- and MALDI-RTOF-MS-generated abundant protonated and/or cationized molecules (ammoniated or sodiated) from the liquid/liquid extract. Only ESI-IT-MS allowed simultaneous detection of all three analytes in the extract of insulation claddings. The latter two so-called 'soft' desorption/ionization techniques exhibited intense fragmentation only by applying low-energy collision-induced dissociation (CID) tandem MS on a multistage ion trap-instrument and high-energy CID on a tandem TOF-instrument (TOF/RTOF), respectively. Strong differences in the fragmentation behavior of the three analytes could be observed between the different CID spectra obtained from either the IT-instrument (collision energy in the very low eV range) or the TOF/RTOF-instrument (collision energy 20 keV), but both delivered important structural information.

CID of singly charged antioxidants applied in lubricants by means of a 3D ion trap and a linear ion trap–Orbitrap mass spectrometer

“…This cleavage is usually rarely observed by LE-CID utilizing IT instruments. [14] In contrast, LE-CID of the corresponding [M−H] − -precursor ion (m/z 641 3872) of compound 2 did not show any cleavages at the tertiary butyl-substituent sites (Fig. 2(C)).…”

“…Although likely, a possible involvement of a tertiary butyl group in loss of neutral ethene would require a rather complex rearrangement reaction in the gas phase probably based on a McLafferty-type rearrangement process. [14] As this fragmentation reaction is not feasible based on MS 2 experiments, isotope labeling of the analyte would be necessary to elucidate the exact reaction mechanism. Though, in the interpretation of the 3D-ITMS spectra (Fig.…”

“…Interestingly, among other fragmentation pathways, C-C bond cleavages were observed. [14] These properties of the antioxidants complicate the characterization of not only antioxidants but also their oxidation products as well as other degradation products. Therefore, detailed investigation of the mass spectrometric fragmentation behavior of selected compounds with a known chemical structure, which are representative for the different classes of antioxidants, is essential.…”

Quantitative Analysis of Polymer Additives with MALDI-TOF MS Using an Internal Standard Approach

“…di-tert.butylphenol derivatives) but differentiation between individual species is not possible and quantification very complicated. Other methods presented only recently are the analysis of the solid samples by DESI [7], ASAP [8], DART [9], or SIMS [10]. In DESI (Desorption Electrospray Ionization) and DART (Direct Analysis in Realtime), the surface of a polymer is either put into an ESI spray or a helium stream, both resulting in the ionization of the volatile components of the sample.…”

Ambient analysis of leachable compounds from single‐use bioreactors with desorption electrospray ionization time‐of‐flight mass spectrometry

“…Direct analysis of organic compounds including polymer additives in a solid sample has been demonstrated using an array of MS‐based techniques such as pyrolysis‐gas chromatography/MS, atmospheric pressure solid probe, matrix‐assisted laser desorption/ionization time‐of‐flight (TOF)MS, and secondary ion mass spectrometry . With the recent development of ambient ionization techniques, such as direct analysis in real time and desorption electrospray ionization (DESI), direct analysis of solid‐phase samples has become especially attractive since minimum or no sample pretreatment is required prior to the analysis, allowing rapid sample measurements.…”