Analysis of Antioxidants in Polyethylene Using Supercritical Fluid Extraction/Supercritical Fluid Chromatography and Infrared Detection

Abstract

Supercritical fluid extraction using 100% carbon dioxide is able to remove antioxidant additives from flaked polyethylene. SFE appears to be more selective for the lower-range low-MW polymer than Soxhlet-type extraction. This yields a chromatogram with less interference from low-MW polymer peaks in the region where the additive components elute. Infrared detection is able to locate peaks corresponding to distinct types of additives by generating chromatograms from chemically specific regions of the SFC/IR data. Infrared spectra are sufficient for identification of additives and determination of the oxidation state of phosphorus-containing antioxidants.

Phosphite additives and their transformation products in polyethylene packaging for G-irradiation

“…They assigned a 998 cm ¡1 peak to phosphate and a 856 cm ¡1 peak to phosphite. The IR spectrum of our oxidized PI-1 (PA-1 in ® gure 2) is in fact an excellent ® t with the IR of the major product reported by Weiboldt et al (1990), but for which they lacked an authentic standard.…”

“…In general, phosphites and phosphates can be readily discriminated by IR (Corbridge 1969). Weiboldt et al (1990) have identi-® ed products from PI-1 by IR analyses on super critical chromatography fractions from extracted PE. They assigned a 998 cm ¡1 peak to phosphate and a 856 cm ¡1 peak to phosphite.…”

Mass spectrometric analysis of additives in polymer extracts by desorption chemical ionization and collisional induced dissociation with B/E linked scanning

“…fluid extraction has emerged as a rapid and efficient method for extracting organic compounds from various matrices. The primary advantages of SFE over liquid phase extraction are that mass transfer of analytes occurs quickly and efficiently and produces no toxic solvent waste [3,10,13,14,28,29].…”

Identification and analysis of polymer additives using packed-column supercritical fluid chromatography with APCI mass spectrometric detection

“…13 SFE has been linked to cSFC-FTIR to analyse antioxidants in polyethylene. 14 In addition, on-line SFE-cSFC-MS studies on polymer additives have been reported. 15,16 All of these applications have used capillary columns, which are capable of providing high resolution, with analysis times between 40 and 60 min.…”