3,5

.related topics


one. ObjectiveTo understand the principle of 3,5-nitrosic acid coloring to determine sugar
Master the operation method of quantitative determination of total sugarII. PrincipleReduced sugar refers to monosaccharides containing free aldehyde or ketones (e.g. glucose) and some reduced bisaccharides (e.g. maltose).
.They can be turned into very active ene glycols under alkaline conditions. In the case of oxidants, it has the ability to restore, and ene glycol itself is oxidized into glycate and other products.

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yellow 3,5-nitrosic acid (DNS)
reagent
and reduced sugar in alkaline conditions after co-heating, itself was reduced to brown-red 3-amino-5-nitrosic acid. Within a certain range, the depth of brown-red in the reaction fluid is directly related to the content of reduced sugar, the absorbance of the solution is measured at a wavelength of 540nm, the standard curve is checked and calculated, the content of reduced sugar in the sample can be found.
for non-reductive bisaccharides (e.g. sucrose) and low-reducing polysaccharides (e.g. starches), they should be thoroughly hydrolysed into monosaccharides by acid hydrolysing. By measuring the reduction of sugar, the total sugar content can be calculated. Since polysaccharine hydrolyzing, a
molecule
water is added to each monosaccharose residue base, so the amount of water added must be deducted from the calculation, and when the polysaccharose content in the sample is much greater than the monosaccharose content, the total sugar content of the color determination should be multiplied by a conversion factor (1 - s 0.9), i.e. the total sugar content in the actual sample must be closer.
three experimental materials and equipment
. 1. Materials
flour
2. Instrument hydrometer
electronics
balance
boiling water bath
3. Equipment
scale
test tube
: 25mL×8
capacity Bottle: 100mL×2
conical bottle: 100mL×1
pipe: 1mL×2 2mL×2 10mL×2
5 cups: 0mL×1 50mL×1
drop tube: 2
wash ear ball: 2
filter paper: f11cm
sit paper funnel
,
wash bottle
, white porcelain plate, test tube rack, pipe pipe holder, test tube clip, glass rod: 1
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