Measurement of ethanol concentration using solvent extraction and dichromate oxidation and its application to bioethanol production process.
A method for measuring the ethanol concentration in a yeast culture broth was developed using both microtubes and a 96-deepwell microplate. The strategy involved first the solvent extraction of ethanol from the yeast culture broth and measurements of the ethanol concentration using the dichromate oxidation method. Particular focus was made on selecting the extraction solvent as well as determining the measurable range of ethanol concentrations using this solvent extraction-dichromate oxidation method. This method was developed as an assay format in 2.0-ml microtubes and 1.2-ml 96-deepwell microplates, and the ethanol concentration in the batch cultures and fed-batch fermentations was measured. Tri-n-butyl phosphate [non-alcoholic solvent, density = 0.9727, solubility in water = 0.028% (w/v)] was used for solvent extraction when measuring the ethanol concentration from the yeast culture broth. The maximum detectable ethanol concentration was 8% (v/v) when 10 g potassium dichromate in 100 ml of 5 M sulfuric acid was used. The concentrations determined from the solvent extraction-dichromate oxidation methods were remarkably similar to those of gas chromatography in which samples were prepared from seven experiments, such as four batch cultures and three fed-batch fermentations.
Seo
Hyun-Beom
HB
Division of Food and Biotechnology, Chungju National University, Jeungpyung, Chungbuk, 368-701, Republic of Korea.
Kim
Hyun-Joo
HJ
Lee
Oh-Kyu
OK
Ha
Ji-Hye
JH
Lee
Hyeon-Yong
HY
Jung
Kyung-Hwan
KH
D001674:Bioelectric Energy Sources; D001709:Biotechnology / Q000295:instrumentation / Q000379:methods*; D002840:Chromates / Q000378:metabolism*; D003470:Culture Media; D000431:Ethanol / Q000032:analysis* / Q000302:isolation & purification; D005285:Fermentation; D010755:Organophosphates / Q000737:chemistry*; D010084:Oxidation-Reduction; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism*; D012997:Solvents / Q000737:chemistry*
D002840:Chromates; D003470:Culture Media; D010755:Organophosphates; D012997:Solvents; D000431:Ethanol; C009524:tributyl phosphate