I work on ethanol production from agricultural wastes. I need to determine the content of ethanol production in media content more carbohydrates by chemical method I not use Gas chromotgrphy method or GC
Dichromate oxidation method is used for ethanol determination.
Caputi A Jr, Ueda M, Brown T (1968) Spectrophotometric determination of ethanol in wine. Am. J. Enol. Vitic. 19: 160-165.
See this paper:
Ka¨gi JHR, Vallee BL. 1960. The role of zinc in alcohol dehydrogenase. V.
The effect of metal-binding agents on the structure of the yeast alcohol
dehydrogenase molecule. Biol Chem 235:3188–3192.
find attachment for determination f ethanol .
Caputi A, Ueda M T Brown T (1968),“Spectrophotometric determination of ethanol in wine”, American Journal of Enol. Vitic 19:L160-165.
If you have the ethanol the only compoenet in your solution you may use refractive index for it
Lucas test is used to identify/estimate secondary and tertiary alcohols. But, the question is about ethanol, which is a primary alcohol. Lucas test gives negative result for primary alcohols. Hence, Lucas test cannot be used for estimation of ethanol.
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 the solvent extraction of ethanol and measurement the ethanol concentration by using the dichromate oxidation method. The article has been attached.
Chemical method for determination of Ethanol concentration is based on the chemistry of complete oxidation of alcohol to carboxylic acid in the presence of good oxidizing agent (eqn i & ii)
ROH → RCHO…………………..eqn i
RCHO → RCOOH…………………eqn ii
use acidified potassium dichromate solution as the oxidizing agent to determine the ethanol. Acidified potassium dichromate is a good oxidizing agent which oxidizes ethanol to ethanoic acid accompanied by color changes from orange to green (eqn iii).
2K2Cr2O7 + 8H2SO4 + 3CH3CH2OH → 2Cr2(SO4) + 2K2SO4 + 3CH3COOH + 11 H2O….eqn iii
Orange-yellow alcohol blue-green
Based on the above principle, prepare a standard curve with known concentration of ethanol (0, 1, 2, 4, 6, 8 & 10 g/L or V/V) . Make up the volume of each standard to 1 ml by distilled water and add 4 ml of K2Cr2O7 to each test tube and mixed thoroughly with a vortex mixer. Incubated at 55°C for 10 min and read absorbance was at 600 nm. Prepare a standard curve of absorbance against concentration.
Take 1 ml of the sample you want to test and subject to the ethanol concentration determination described above. Determine the concentration from your standard curve
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