You are analyzing riboflavin in wheat flour by fluorescence spectroscopy (?ex =
ID: 865991 • Letter: Y
Question
You are analyzing riboflavin in wheat flour by fluorescence spectroscopy (?ex = 450 nm, ?em =530 nm). The extraction procedure is fairly complex. You obtain a 100g sample of the flour. You then weigh out 4.542 g of the flour, add it to a 250 mL volumetric flask, and dilute to volume with 1 N boiling HCl. After thoroughly mixing this solution, you combine 2 mL with 7 mL 1 N HCl. You then freeze-dry 4 mL of the diluted solution, and redissolve the residue to a total volume of 1.5 mL. You combine 0.5 mL of this solution with 0.5 mL ddH2O and measure the fluorescence. The following fluorescence values are obtained for the sample and standards. Prepare a blanked standard curve, and determine the riboflavin concentration in the flour (ppm) (10 points)
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Fluorescence (?ex=450 nm, ?em=530 nm).
Sample
1.706
Riboflavin (20 mg/L)
0.822
Riboflavin (10 mg/L)
0.368
Riboflavin (5 mg/L)
0.121
Riboflavin (2 mg/L)
0.079
Riboflavin (1 mg/L)
0.004
Riboflavin (0 mg/L)
0.476
Flour
Fluorescence (?ex=450 nm, ?em=530 nm).
Sample
1.706
Riboflavin (20 mg/L)
0.822
Riboflavin (10 mg/L)
0.368
Riboflavin (5 mg/L)
0.121
Riboflavin (2 mg/L)
0.079
Riboflavin (1 mg/L)
0.004
Riboflavin (0 mg/L)
0.476
Flour
Explanation / Answer
preparation of standard curve
Below is the standard curve for determination of Riboflavin
Concentration of Riboflavin in Flour is 5917.6ppm
Serial number Conc(mg/L) absorbance 1 0 0.004 2 1 0.079 3 2 0.121 4 5 0.368 5 10 0.822 6 20 1.706Related Questions
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