A simple contactless impedance probe for determination of ethanol in gasoline

• Published in: Analytica chimica acta Vol. 694; no. 1; pp. 57 - 60
• Main Authors: Opekar, F., Čabala, R., Kadlecová, T.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 23.05.2011; Elsevier
• Subjects: Analytical chemistry; Chemistry; Chromatographic methods and physical methods associated with chromatography; Contactless impedance detection; Dielectric constant; Ethanol; Ethyl alcohol; Exact sciences and technology; Gas chromatographic methods; Gasoline; GC–MS; Impedance probes; Mathematical analysis; Multivibrators; Permittivity; Planar cell; Spectrometric and optical methods; Tubular cell; Tubular cell; Planar cell; GC–MS; Ethanol; Contactless impedance detection; Gasoline; Sample; Standard; Concentration; Probe; GC-MS; Gas chromatography; Additive; Frequency; Limit; Pretreatment; Detection; Reliability; Impedance; Capacitor; Permittivity; Mass spectrometry; Non contact measurement
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2011.03.038

A contactless impedance probe with either a planar or a tubular detection cell has been developed and tested for rapid determination of the ethanol content in gasoline. The probe cell is connected as a capacitor determining the frequency of an electronic astable multivibrator. The multivibrator frequency depends on the permittivity of the test gasoline in the detection cell which is strongly influenced by the ethanol content as one of the major polar additives. The ethanol concentrations obtained with the impedance probe agree, within the reliability interval, with those obtained by GC–MS measurements and fall into the limits recommended by the appropriate European Standard. The gasoline samples are analyzed without any pretreatment.