Temperature-programmed packed capillary liquid chromatography coupled to evaporative light-scattering detection and electrospray ionization time-of-flight mass spectrometry for characterization of high-molecular-mass hindered amine light stabilizers.
High-molecular weight-hindered amine light stabilizers (HMW-HALSs) are of utmost importance in modern polyolefin stabilization technology and in-depth knowledge about their chemical composition, particularly the oligomers, is essential for development of new and more efficient stabilizers. In the present study, the applicability of temperature-programmed packed capillary LC coupled to miniaturized ELSD and positive mode ESI-TOF-MS for analysis of HMW-HALSs is demonstrated through extensive characterization of two state-of-the-art stabilizers, i.e., HALS-1 and HALS-2. Both stabilizers were individually separated on a 320 microm i.d. x 35 cm long Hypersil 3 microm ODS-100 column using a temperature program from 30 to 120 degrees C and a quaternary mixture of ethylacetate, acetonitrile, triethylamine (TEA) and acetic acid (45.0:44.9:10.0:0.1 (v/v/v/v)) as the mobile phase. The effect of using various amounts of ethylacetate, acetonitrile and triethylamine in the mobile phase on the chromatographic separation is demonstrated. Furthermore, the LC-ESI-TOF-MS analyses revealed that HALS-1 (oligomeric) was highly complex and consisted of at least five different mass series, while HALS-2, which was assumed to be monomeric, contained two different mass series. Chemical structures for nearly all species of both stabilizers are proposed.
Andersen
Thomas
T
Department of Chemistry, University of Oslo, P O. Box 1033, Blindern, N-0315 Oslo, Norway. than@kjemi.uio.no
Skuland
Inger L
IL
Holm
Anders
A
Trones
Roger
R
Greibrokk
Tyge
T
D000588:Amines / Q000737:chemistry*; D002853:Chromatography, Liquid / Q000379:methods*; D008027:Light; D008970:Molecular Weight; D012542:Scattering, Radiation; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013696:Temperature
D000588:Amines