title: Vapor permeation-stepwise injection simultaneous determination of methanol and ethanol in biodiesel with voltammetric detection.
abstract: A novel vapor permeation-stepwise injection (VP-SWI) method for the determination of methanol and ethanol in biodiesel samples is discussed. In the current study, stepwise injection analysis was successfully combined with voltammetric detection and vapor permeation. This method is based on the separation of methanol and ethanol from a sample using a vapor permeation module (VPM) with a selective polymer membrane based on poly(phenylene isophtalamide) (PA) containing high amounts of a residual solvent. After the evaporation into the headspace of the VPM, methanol and ethanol were transported, by gas bubbling, through a PA membrane to a mixing chamber equipped with a voltammetric detector. Ethanol was selectively detected at +0.19 V, and both compounds were detected at +1.20 V. Current subtractions (using a correction factor) were used for the selective determination of methanol. A linear range between 0.05 and 0.5% (m/m) was established for each analyte. The limits of detection were estimated at 0.02% (m/m) for ethanol and methanol. The sample throughput was 5 samples h(-1). The method was successfully applied to the analysis of biodiesel samples.
authors.affiliation: Institute of Chemistry, St. Petersburg State University, Universitetsky pr. 26, Saint Petersburg 198504, Russia. Electronic address: andrey.shishov.rus@gmail.com.
authors.forename: Andrey
authors.initials: A
authors.lastname: Shishov
authors.affiliation: Institute of Chemistry, St. Petersburg State University, Universitetsky pr. 26, Saint Petersburg 198504, Russia.
authors.forename: Anastasia
authors.initials: A
authors.lastname: Penkova
authors.affiliation: Institute of Chemistry, St. Petersburg State University, Universitetsky pr. 26, Saint Petersburg 198504, Russia.
authors.forename: Andrey
authors.initials: A
authors.lastname: Zabrodin
authors.affiliation: Institute of Chemistry, St. Petersburg State University, Universitetsky pr. 26, Saint Petersburg 198504, Russia.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Nikolaev
authors.affiliation: Institute of Chemistry, St. Petersburg State University, Universitetsky pr. 26, Saint Petersburg 198504, Russia.
authors.forename: Maria
authors.initials: M
authors.lastname: Dmitrenko
authors.affiliation: Institute of Chemistry, St. Petersburg State University, Universitetsky pr. 26, Saint Petersburg 198504, Russia.
authors.forename: Sergey
authors.initials: S
authors.lastname: Ermakov
authors.affiliation: Institute of Chemistry, St. Petersburg State University, Universitetsky pr. 26, Saint Petersburg 198504, Russia.
authors.forename: Andrey
authors.initials: A
authors.lastname: Bulatov
mesh_terms: D056804:Biofuels / Q000032:analysis*; D000431:Ethanol / Q000032:analysis*; D017022:Flow Injection Analysis / Q000379:methods; D000432:Methanol / Q000032:analysis*; D010539:Permeability; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014835:Volatilization
chemical_list: D056804:Biofuels; D000431:Ethanol; D000432:Methanol
keywords: Biodiesel; Cyclic voltammetry; Ethanol; Flow analysis; Methanol; Vapor permeation