I have 1 ml of chlorella vulgaris pellet + 2 ml of ethanol 70% , after incubation , i took 50 µl of the supernatant + 950 µl of water and 2 ml of anthrone. Now i have a standard curve of glucose (range: 0,01-0,1 mg/ml), how i can calculate the amount of carbohydrates in my 1 ml sample of algae ? NB: The algae suspension are under chemicals stress and they're dying so i can have the same weight in pellet, that why i use 1 ml instead of dry sample in mg. Thanks for the answer
Dear Christiane,
Presuming you measured the absorbance at 620 nm, I would suggest you to obtain the slope from the std. curve and the inverse of that will give you the std. factor of the curve. You can use that factor value to multiply with the absorbance read by you for the sample. The value obtained then should provide the concentration of glucose in mg/ml unit. If you have diluted the aliquot of the sample prior to read the absorbance, then you will have multiply the concentration value with that of the dilution degree. After that you need to consider the amount of pelleted algae you have used while preparing the solution to begin with since your explanation lacked the crucial part of the volume of solvent/fluid used to prepare the 1 ml solution and also the weight of the pellet used in the first place. Considering that dilution which you know, you should end up with the value of glucose as mg/g dry weight of the pellet. Since you have employed the anthrone method, complex carbohydrates were mostly, if not all, hydrolyzed and were converted to simplest monosaccharides, here treated as glucose. Hence the final amount of glucose is the near indirect concentration of the total carbohydrates present within the sample.
I hope you will be able to find the answer to your query.
Best regards
Dr. Abhishek Mukherjee
Based on the plotted standard curve, calculate carbohydrate in sample through the following equation:
X = (AABS – q)/m
where,
X = carbohydrate concentration in sample (mg/ml),
AABS = observed absorbency of sample
m = slope value of the standard curve, and
q = intercept value of the standard curve.
Since you are using 1 ml of chlorella vulgaris pellet , please note the dry weight of the 1 ml of chlorella vulgaris in mg.
how about the standards? did u used 50 µl of standards + 950 µl of water and 2 ml of anthrone? if yes...
From the calculated carbohydrate concentration, percentage of carbohydrate in the chlorella vulgaris sample (% dry weight) can be calculated through the following equations:
Y = (MX /Ma) x 100%
Ma = (Wa/Vex)
where,
Y = percentage of carbohydrate in sample (% dry weight),
MX = carbohydrate concentration (mg/mL),
Ma = algal biomass concentration (mg/mL)
Wa = dry weight of algal sample (mg), and
Vex = volume of extraction solution, 2 ml of ethanol 70%
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