after determination of the concentration of sample based on the absorbance using regression equation obtained from the calibration curve
how to calculate total of Polysaccharides content in the sample % (w/w)
taking example from reseach paper attached
using regression equation obtained from the calibration curve
Y=.009x-0.026
For k (s) y= 0.155
x= 20 ug/ml
how to they got got 1.49 total of Polysaccharides content in the sample % (w/w)
Preparation of sample
Dissolve about 10mg of powder drug in 100ml of distilled in water. From this use 1ml for sugar analysis to estimate the polysaccharide content in K. pinnatum & K. crenata, add 1ml of 5% phenol to the 1ml of sample solution, and then add 5ml of concentrated H2SO4 and measure the absorbance after 10 minutes at 488nm against blank. Then compare it with standard solution of glucose
Dear Alahdal h.,
Generally, if you use this kind of st. curve (ug/mL) you can calculate your final results as: multiply concetracition that you find by the curve equation (ug/mL) by dulution factor (if you dilute your sample) and after that divide to the concentration of your sample solution (in ug/mL). To convert to % just multiply by 100. Keeping in mind the dry solids of your plant material.
Parenthetically, do you think that the chosen method and sample preparation actually reflects the total carbohydrate content!?
I wish you success in your project tasks.
In general it is not advisable to take regression parameters in colorimetric assays from the literature as these constants are usually dependent on the exact experimental conditions. So, I recommend you to construct your own calibration curves. There are some additional complications:
- As pointed out by Marcus Nagle, low MW saccharides may be present in a sample. These can be removed by dialysis or by precipitation of an aqueous sample suspension with ethanol. Of course the mass loss has to be accounted for.
- Plant polysaccharides do not only consist of glucose but may also contain other monosaccharides like xylose, arabinose, etc. These sugars may give a different response in the phenol-sulfuric acid assay.
- Non-carbohydrate compounds like lignin, proteins and lipids in the sample may interfere with the assay. Interference can be explored by a standard addition experiment: adding known amounts of glucose to the sample and look if the increments in absorbance are similar to those for pure glucose.
Summarizing, without precautions the literature method is likely to give only a rough estimate of polysaccharide content of complex samples.
If the polysaccahride conc is 12 microgm/ml and dilution factor is 250 what is the % of carbohydrate content.
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