title: Experimental design approach for the optimisation of pressurised fluid extraction of additives from polyethylene films.
abstract: A pressurised fluid extraction (PFE) and normal-phase-high performance liquid chromatography (NP-HPLC) method is proposed for the determination of additives in polyethylene films. The study of PFE variables was performed using a Plackett-Burman (PB) experimental design for screening and a central composite design (CCD) for optimising the main variables obtained from the Pareto charts. The studied variables were: temperature, time, cyclohexane (CHx) and tetrahydrofuran (THF) as modifiers, flush volume and extraction cycles, and an isopropanol:CHx (92.5:7.5) mixture twice at 105 degrees C for 15 min were the final conditions selected. The additives in the PFE extracts were separated by NP-HPLC using a silica column and a gradient n-hexane:dichloromethane:acetonitrile mobile phase. Additive solubility is higher in normal-phase solvents; thus, their separation can be carried out at room temperature. Finally, the method was applied to determine additives in several polyethylene films.
authors.affiliation: Chemistry Department, University of La Rioja, C/Madre de Dios 51, E-26006 Logroño, La Rioja, Spain.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Garrido-López
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Tena
mesh_terms: D020959:Polyethylene / Q000737:chemistry*; D011312:Pressure
chemical_list: D020959:Polyethylene