Separation and identification of an oligomeric light stabilizer Chimassorb 944 by gradient elution chromatography coupled with matrix-assisted laser desorption/ionization mass spectrometry

Hindered amine light stabilizers are an important class of stabilizers that protect synthetic polymers from degradation and thus from changing mechanical and optical properties. The current study presents an HPLC method capable of separating oligomeric hindered amine light stabilizers on a commercially available stationary phase, employing an MS-compatible novel mobile phase. Based on the exact masses observed with Q-TOF-MS, a comprehensive characterization of five different types of oligomeric hindered amine light stabilizers was achieved, leading to structural information not included in the datasheets provided by the suppliers. For the different investigated hindered amine light stabilizers, a number of recurring units up to 17 and a molecular weight of 5200 g/mol were detected. Furthermore, the analysis of stabilizer extracts of processed polypropylene samples containing different types of hindered amine light stabilizers revealed significant differences in the oligomeric pattern between standards and polymer samples. Thus, changes in the analytes' oligomeric pattern resulting from processing or aging of polymer materials can be monitored with the presented method.

Section: Resultssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Separation and characterization of oligomeric hindered amine light stabilizers using high‐performance liquid chromatography with UV and quadrupole time‐of‐flight mass spectrometric detection

Hintersteiner

Reisinger

Himmelsbach

et al. 2016

“…The number‐ and weight‐average molar masses, M n , M w , of ethyl silicate‐40 and their corresponding degrees of polymerization, n n , n w , were calculated by the following formulas :

{normalM}_{normaln} = \sum {normalc}_{normali} / \sum {(c}_{normali} {/ M}_{normali})

M_{normalw} = \sum (c_{normali} M_{normali}) / \sum c_{normali}

n_{normaln} = M_{normaln} / M_{normalo}

n normalw = M_{normalw} / M_{normalo}

where i is the increment index; c i refers to the weight concentration of oligomer molecules with molar mass M i , and M o is the formula weight of the repeating unit in the macromolecules.…”

Section: Methodsmentioning

confidence: 99%

“…However, there are very few reports in the literature on the application of ESI‐MS or MALDI‐MS to analysis of ethyl silicates. RP‐HPLC has been used extensively for the separation and quantification of synthetic oligomers/polymers over the last three decades . A distinct advantage of this technique is that individual oligomeric species are eluted in the order of increasing number of repeat units, thus enabling well‐resolved separation of individual oligomers within reasonable analysis time to be achieved under gradient elution conditions.…”

Section: Introductionmentioning

confidence: 99%

Separation and identification of oligomeric ethyl silicates by liquid chromatography with electrospray ionization mass spectrometry

Xiu-li

Wan

2015

Self Cite

Reversed-phase liquid chromatography coupled with electrospray ionization mass spectrometry was used to study the molecular structures of components and molar mass distributions in ethyl silicate-40, a versatile liquid precursor for silicon-based materials. Identity testing by standard spectroscopic techniques showed that a commercial sample of ethyl silicate-40 was composed of linear/branched ethoxysiloxane oligomers with the silicon atoms ranging from 2 to 12 together with minor monocyclic species. Analysis of the sample by liquid chromatography coupled with evaporative light scattering detection resulted in an elution profile consisting of a series of peak clusters. Peak identification showed that the linear/branched homologous series of oligomers were eluted in the order of increasing number of silicon atoms in the molecules and the time duration (width) of the resulting peak clusters increased in the same fashion corresponding to increasing number of geometric isomers. In addition, small amounts of monocyclic oligomers present in the sample were found to be less retained than each linear/branched counterpart. Finally, the molar mass distribution parameters for ethyl silicate-40 determined by the developed method were in good agreement with the literature values. Overall, this work demonstrates that reversed-phase liquid chromatography coupled with electrospray ionization mass spectrometry is an indispensable tool for the comprehensive characterization of complex mixtures of this type.

“…During the last years some methods for the characterization of oligomeric HALS have been published, including CZE , HPLC , and mass spectrometric techniques . However, the suitability of these methods for rapid quantitative routine analysis is limited.…”

Section: Introductionmentioning

confidence: 99%

Rapid determination of oligomeric hindered amine light stabilizers in polymeric materials

Kreisberger

Buchberger

2017

Hindered amine light stabilizers are essential for the stabilization of synthetic polymers, particularly for materials used for outdoor applications. Although up to now a considerable number of studies dealing with the analytics of this class of stabilizers had been published, especially the determination of oligomeric hindered amine light stabilizers is still an analytical challenge. In the current work, a fast and simple liquid chromatographic method for the quantitative determination of oligomeric hindered amine light stabilizers is presented. A key aspect of this method is their completely different retention behavior depending on the pH, enabling a single peak elution approach by a pH gradient run. This allows a quantitation with simple UV detection independent of the actual oligomeric composition. Calibration curves within the concentration range relevant for the analysis of real polymer samples (LOQ = 70 mg/L) were constructed with R values above 0.99. Spiked extracts from polyolefin samples showed recovery rates between 97.3 and 102.9% for five different commercial hindered amine light stabilizers. Relative standard deviations were between 2.0 and 3.9%. Furthermore, it was demonstrated that the employed approach can be easily adapted for mass spectrometry detection.