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Desorption electrospray ionisation mass spectrometry reveals in situ modification of a hindered amine light stabiliser resulting from direct N-OR bond cleavage

Journal Article


Abstract


  • Detection and characterisation of structural modifications of a hindered amine light stabiliser (HALS) directly from a polyester-based coil coating have been achieved by desorption electrospray ionisation mass spectrometry (DESI-MS) for the first time. In situ detection is made possible by exposing the coating to an acetone vapour atmosphere prior to analysis. This is a gentle and non-destructive treatment that allows diffusion of analyte to the surface without promoting lateral migration. Using this approach a major structural modification of the HALS TINUVIN®123 (bis(1-octyloxy-2,2,6,6-tetramethyl-4- piperidyl) sebacate) was discovered where one N-ether piperidine moiety (N-OC8H17) is converted to a secondary piperidine (N-H). With the use of 2-dimensional DESI-MS imaging the modification was observed to arise during high curing temperatures (ca. 260°C) and under simulated physiological conditions (80°C, full solar spectrum). It is proposed that the secondary piperidine derivative is a result of a highly reactive aminyl radical intermediate produced by N-O homolytic bond cleavage. The nature of the bond cleavage is also suggested by ESR spin-trapping experiments employing α-phenyl-N-tert-butyl nitrone (PBN) in toluene at 80°C. The presence of a secondary piperidine derivative in situ and the implication of N-OR competing with NO-R bond cleavage suggest an alternative pathway for generation of the nitroxyl radical - an essential requirement in anti-oxidant activity that has not previously been described for the N-ether sub-class of HALS. © 2011 The Royal Society of Chemistry.

Authors


  •   Paine, Martin (external author)
  •   Barker, Phil J.
  •   Blanksby, Stephen J. (external author)

Publication Date


  • 2011

Citation


  • Paine, M., Barker, P. J. & Blanksby, S. J. (2011). Desorption electrospray ionisation mass spectrometry reveals in situ modification of a hindered amine light stabiliser resulting from direct N-OR bond cleavage. The Analyst, 136 (5), 904-912.

Scopus Eid


  • 2-s2.0-79951642764

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/5255

Number Of Pages


  • 8

Start Page


  • 904

End Page


  • 912

Volume


  • 136

Issue


  • 5

Abstract


  • Detection and characterisation of structural modifications of a hindered amine light stabiliser (HALS) directly from a polyester-based coil coating have been achieved by desorption electrospray ionisation mass spectrometry (DESI-MS) for the first time. In situ detection is made possible by exposing the coating to an acetone vapour atmosphere prior to analysis. This is a gentle and non-destructive treatment that allows diffusion of analyte to the surface without promoting lateral migration. Using this approach a major structural modification of the HALS TINUVIN®123 (bis(1-octyloxy-2,2,6,6-tetramethyl-4- piperidyl) sebacate) was discovered where one N-ether piperidine moiety (N-OC8H17) is converted to a secondary piperidine (N-H). With the use of 2-dimensional DESI-MS imaging the modification was observed to arise during high curing temperatures (ca. 260°C) and under simulated physiological conditions (80°C, full solar spectrum). It is proposed that the secondary piperidine derivative is a result of a highly reactive aminyl radical intermediate produced by N-O homolytic bond cleavage. The nature of the bond cleavage is also suggested by ESR spin-trapping experiments employing α-phenyl-N-tert-butyl nitrone (PBN) in toluene at 80°C. The presence of a secondary piperidine derivative in situ and the implication of N-OR competing with NO-R bond cleavage suggest an alternative pathway for generation of the nitroxyl radical - an essential requirement in anti-oxidant activity that has not previously been described for the N-ether sub-class of HALS. © 2011 The Royal Society of Chemistry.

Authors


  •   Paine, Martin (external author)
  •   Barker, Phil J.
  •   Blanksby, Stephen J. (external author)

Publication Date


  • 2011

Citation


  • Paine, M., Barker, P. J. & Blanksby, S. J. (2011). Desorption electrospray ionisation mass spectrometry reveals in situ modification of a hindered amine light stabiliser resulting from direct N-OR bond cleavage. The Analyst, 136 (5), 904-912.

Scopus Eid


  • 2-s2.0-79951642764

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/5255

Number Of Pages


  • 8

Start Page


  • 904

End Page


  • 912

Volume


  • 136

Issue


  • 5