25mg of glycogen is supplied – what is its’ percentage purity?
The glycogen sample was hydrolysed to glucose monomers with 2ml of 2M sulphuric acid in water. The hydrosylate was then neutralised and made up to 10ml total volume. The glucose content was assayed enzymatically and the results gave a content of 2.35mg/ml of glucose. Remember glycogen is a polymer of glucose made via a condensation reaction between glucose monomers losing water during the condensation and that hydrolysis reverses this process.
In the 10 mL sample you have 2.35 mg/mL. So in 10 mL you have 2.35 x 10 = 23.5 mg. The sample was 25 to start. 23.5/25.0 is what percentage.
Well, to calculate the percentage purity of the glycogen, we need to know how much glycogen was originally present. Unfortunately, we have been given the glucose content after hydrolysis, not the original amount of glycogen. So, without that information, it's impossible to determine the percentage purity.
But hey, I guess you could say the purity of the sample is 100% in terms of being completely pure glucose! So, there's a silver lining to not having all the necessary data. Keep those positive thoughts flowing!
To find the percentage purity of the glycogen sample, we need to calculate the amount of glycogen present in the 25mg sample.
1. Calculate the amount of glucose in the 10ml hydrosylate:
Given the glucose content is 2.35mg/ml:
Amount of glucose = 2.35mg/ml * 10ml = 23.5mg
2. Since glycogen is a polymer of glucose, we need to convert the amount of glucose to glycogen. The molar mass of glucose is 180.16 g/mol, and glycogen is an average of 162.14 g/mol per glucose unit (as it is a branched polymer). Therefore:
Amount of glycogen = (23.5mg * 162.14g/mol) / 180.16g/mol = 21.16mg
3. Finally, calculate the percentage purity of the glycogen sample:
Percentage purity = (Amount of glycogen / Initial sample weight) * 100
Percentage purity = (21.16mg / 25mg) * 100 = 84.64%
Therefore, the percentage purity of the glycogen sample is approximately 84.64%.
To calculate the percentage purity of the glycogen sample, we need to compare the amount of glucose obtained from the enzymatic assay with the amount we would expect based on the amount of glycogen used.
Here's how you can calculate the percentage purity:
1. Convert the volume of the hydrolysate to the amount of glucose: Since the glycogen was hydrolyzed to glucose monomers, we can assume that the amount of glucose obtained is directly proportional to the volume of the hydrolysate. In this case, we have 2.35 mg of glucose in 1 ml of hydrolysate.
2. Calculate the total amount of glucose obtained: Multiply the volume of the hydrolysate (10 ml) by the concentration of glucose (2.35 mg/ml) to get the total amount of glucose obtained. In this case, the total amount of glucose obtained is 10 ml x 2.35 mg/ml = 23.5 mg.
3. Calculate the expected amount of glucose from the amount of glycogen: Since glycogen is a polymer made of glucose, we need to account for the conversion of glucose to glycogen during polymerization. Each glucose unit in the glycogen molecule weighs 180.16 g/mol. Multiply this by the amount of glycogen used (25 mg) and then divide by the molar mass of glucose (180.16 g/mol) to calculate the expected amount of glucose. In this case, the expected amount of glucose is (25 mg * 180.16 g/mol) / 180.16 g/mol = 25 mg.
4. Calculate the percentage purity: Divide the actual amount of glucose obtained (23.5 mg) by the expected amount of glucose (25 mg) and then multiply by 100 to get the percentage purity. In this case, the percentage purity is (23.5 mg / 25 mg) * 100 = 94%.
Therefore, the percentage purity of the glycogen sample is 94%.