The preparation, assay and certification of aqueous ethanol reference solutions

Measurement of ethanol concentration using solvent extraction and dichromate oxidation and its application to bioethanol production process

“…Dichromate oxidation method is recently used for the measurement of ethanol in a Xow injection analysis [8,11,20]. Moreover, the international ethanol reference solution is prepared by the dichromate oxidation method [3]. Meanwhile, in the culture broth for bioethanol production, it is probable that unhydrolyzed insoluble material exists and its color is dark.…”

Inexpensive Procedure for Measurement of Ethanol: Application to Bioethanol Production Process

“…Solvent extraction in this ethanol measurement is a crucial step because glucose, yeast extract, peptone, CSL, and glycerol can cause a change in color through a reaction with dichromate and their intrinsic colors can also affect the final reaction color [7]. In other words, without the ethanol extraction step, the measured ethanol concentration in the culture medium may be tainted by a direct reaction between the dichromate reagent and the other components in the culture medium.…”

“…It has been reported that the dichromate oxidation method can be used directly to determine the ethanol concentration in culture broths of yeast like Candida shehatae, Saccharomyces cerevisiae, Pichia kudriavzevii and Candida tropicalis [9] [10]. When ethanol is present in an aqueous solution, chromium ions oxidize ethanol, and these ions are reduced from the +6 oxidation state to +3 and changing the color from [7]. Moreover aliphatic alcohol like n-dodecanol or n-decanol is a representative solvent for extracting ethanol from a culture broth and benzyl alcohol had been used as an alternative to distillation [11] [12].…”

“…In saccharification, enzymatic degradation of complex sugars produces additional components as byproducts. These could react directly or indirectly with dichromate reagent, thus may interfere with reaction color [6] [7]. Therefore, the extraction of ethanol from the culture broth is essential before the assay is performed.…”

Stoichiometric approach to redox back titrations in ethanol analyses

“…This paper concerns calculations involved with determination of ethanol contents, taken as interesting examples of classical, titrimetric analysis. Importance of classical determination of this analyte is revealed by the facts that: (1) a variety of analytical procedures were suggested for the ethanol determination [1][2][3][4][5][6][7][8][9][10][11]; (2) the international ethanol reference solution is prepared by the dichromate oxidation method [12].…”