What mass of riboflavin (in mg) must be dissolved in 0.02 M acetic acid solution

Question

What mass of riboflavin (in mg) must be dissolved in 0.02 M acetic acid solution (Solution #1, assume density is 1.0 g/mL) to create 500 mL of a 50.0 ppm standard solution of riboflavin (Solution #2)?

Determine the volume of Solution #2 that is needed to make 25.00 mL of 2ppm solution?

Calculate the percent riboflavin (to 3 significant figures) in a 50 mg multivitamin that was dissolved in 250 mL of 0.02 M acetic acid (assume density of acetic acid = 1 g/mL), given the fluorescence of the multivitamin is 0.142.

Explanation / Answer

1 Part per million = 1 mg/L H20

50 ppm = 50 mg/ L H20

50 ppm = x mg/0.5 L = 25 mg Riboflavin

C1V1 = C2V2

50ppm * x = 2 ppm * 25 mL

x = 1 mL

I think the last question is not possible unless you provide a calibration curve or line of best fit for riboflavin flouresence for multiple ppm concentrations.

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