Determination of soluble sugar content: ketone method.

the purpose of . 1. Understand the principle of the ketone method to determine soluble sugar content
2. Learn to find the standard curve equation - least square multiplication
3. Master the use of
-photometricexperimental principleFast and convenient method of sugar, under strong acidic conditions, ketones can be free or polysaccharides in the presence of hexalose, sugar and hexalic acid (reduced and non-reductive) to produce blue-green glycoaldehyde derivatives, the depth of its color and sugar content in a certain range of positive ratio. Ketones can also react with other sugars, but appear in different colors. When there is a protein containing more tryptophan
protein
, the reaction is unstable and appears red. The above-mentioned specific sugar substances, the response is more stable.
reaction:

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.. Features of the method: high sensitivity, small measurement, fast and convenient.experimental step
1. Find the standard curve equation
take 6
test tubes
, according to the table preparation (removal) glucose (G) standard solution, boiling 7 minutes to take out, with tap water cold to room temperature, with 721 d'photons to score color, wavelength 620nm, 1 tube as a ratio (reserved), to find the standard curve equation. (G concentration of 200 μg/mL, ketone
reagents
:2 g ketones / 85% H
2
SO
4 ) per litre After accurately claiming 1.00 g shredding, put in a large test tube, add 25mL distilled water, boil for 10 minutes, filter into a 250mL
capacity bottle
(can be pumped) through
funnel
, and extract it twice with boiling distilled water, filter fluid into the capacity bottle,
the
on the filter paper is flushed twice with water and cooled to the scale.
(2) absorbs 0.5mL of the filter in the numbered three test tubes, replenishes 1.00mL with distilled water, and absorbs 1.00mL of the filter from the three test tubes numbered separately, with the ketone reagent 5. 0mL (operated in a cold water bath), shake well and boil in a boiling water bath for 7 minutes, remove and cool to room temperature, in order to standard curve of the 1 s tube as a score, with 721 d'photometer at 620nm to measure the absorbance or pass rate.
the formula for the standard curve equation using the least square multiplication method: . X:G concentration (sg/mL)Y: absorbance A-logT
This experiment requires the correlation coefficient r≥0.99
.