can i get assistance with a chemistry calculation question please

[heymanhowareyou]

Hi im sorry i dont know if this is the correct forum to ask this question in but here it is:
I need to calculate the riboflavin content for a solution. It was made from 1 vitamin tablet dissolved in 20ml of water. Then the solution was made up to 100ml with neutral buffer. Then a 1:50 dilution was made with the solution. The concentration of riboflavin in the 1:50 solution was 86 μg/L. I need to know the riboflavin content in the tablet, in mg. Could anyone be kind enough to help me with this please. 

 

Here is what i have done for this. I am not very confident in it and im afraid that it may be incorrect.

 

1 tablet in 20ml > made to 100 ml > 1 in 50 dilution

Total dilution factor = 1/20 * 1/5 * 1/50 = 1/5000

Approximate concentration of tablet solution using the standard curve is 86 mg/L in diluted solution.

86 x 5000 = 430000 mg/L = 430 mg/L

In 100 ml solution = 430/10 = 43 mg

In 20 ml solution = 8.6 mg

 

Tablet riboflavin content is 8.6 mg.

Please help, THank you.

[John Cuthber]

There are  a number of ways to look at it.

The 20 ml is a bit of a red herring.

[heymanhowareyou]

Hi so if i did this:

86 x 50 / 10 = 430 ug in 100ml. would that be correct? so would there be 430 ug of riboflavin in the tablet?

[John Cuthber]

Where did the 10 come from?
There are lots of ways to look at it

86 µg/ml in the diluted solution means 50 x 86 µg/ml in the original solution. That's 4300 µg /ml

And there was 100 ml of it 

So, how much was there in that original solution?

[heymanhowareyou]

sorry the concentration in the diluted solution was 86 ug/L. The solution that the dilution was made from was 100ml.