title: A sequential enzymatic microreactor system for ethanol detection of gasohol mixtures.
abstract: A sequential enzymatic double microreactor system with dilution line was developed for quantifying ethanol from gasohol mixtures, using a colorimetric detection method, as a new proposal to the single micro reactor system used in previous work. Alcohol oxidase (AOD) and horseradish peroxidase (HRP) immobilized on glass beads, one in each microreactor, were used with phenol and 4-aminophenazone and the red-colored product was detected with a spectrophotometer at 555 nm. Good results were obtained with the immobilization technique used for both AOD and HRP enzymes, with best retention efficiencies of 95.3 +/- 2.3% and 63.2 +/- 7.0%, respectively. The two microreactors were used to analyze extracted ethanol from gasohol blends in the range 1-30 % v/v (10.0-238.9 g ethanol/L), with and without an on-line dilution sampling line. A calibration curve was obtained in the range 0.0034-0.087 g ethanol/L working with the on-line dilution integrated to the biosensor FIA system proposed. The diluted sample concentrations were also determined by gas chromatography (GC) and high-pressure liquid chromatography (HPLC) methods and the results compared with the proposed sequential system measurements. The effect of the number of analysis performed with the same system was also investigated.
authors.affiliation: Departamento de Engenharia Bioquímica, Escola de Química, Universidade Federal do Rio de Janeiro, C.T., Bl. E, sl 203, Rio de Janeiro, Brasil.
authors.forename: Eliana M
authors.initials: EM
authors.lastname: Alhadeff
authors.forename: Andréa M
authors.initials: AM
authors.lastname: Salgado
authors.forename: Nei
authors.initials: N
authors.lastname: Pereira
authors.forename: Belkis
authors.initials: B
authors.lastname: Valdman
mesh_terms: D000429:Alcohol Oxidoreductases / Q000032:analysis / Q000737:chemistry*; D019149:Bioreactors; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D003124:Colorimetry / Q000295:instrumentation* / Q000379:methods; D045424:Complex Mixtures / Q000032:analysis / Q000737:chemistry; D004800:Enzymes, Immobilized / Q000032:analysis / Q000737:chemistry; D004867:Equipment Design; D019544:Equipment Failure Analysis; D000431:Ethanol / Q000032:analysis* / Q000737:chemistry*; D017022:Flow Injection Analysis / Q000295:instrumentation* / Q000379:methods; D005742:Gasoline / Q000032:analysis*; D006735:Horseradish Peroxidase / Q000032:analysis / Q000737:chemistry*; D008904:Miniaturization; D013057:Spectrum Analysis / Q000295:instrumentation / Q000379:methods
chemical_list: D045424:Complex Mixtures; D004800:Enzymes, Immobilized; D005742:Gasoline; D000431:Ethanol; D000429:Alcohol Oxidoreductases; C019643:alcohol oxidase; D006735:Horseradish Peroxidase