Report Sheet How accurate are nutritional information labels for iron content in

Question

Report Sheet How accurate are nutritional information labels for iron content in vitamins? Name Hanno A Yus Date Questions must be answered in complete sentences on a separate sheet. Remember to attach your calibration plot and one sample concentration calculation. 1. Calibration Absorbance (AU) Concentration (of the standard) standard 1.0. Bos LM Standard 2 o Standard 3 0.323 -3M B) (7266 g Standard 4 Standard 5 ob40 SM k o l&from; your calibration curve) 2. Unknown Prenertal Wuttiita win Unknown ID name mg iron in vitamin mg irong vitamin Absorbance Concentration Trial 0169 2 12s RSD

Explanation / Answer

Determination of Fe in vitamins

1) Prepare standard solutions of known concentration

2) measure absorbance of each solution.

3) Plot absorbance versus concentration of Fe in M

For unknown solution

4) determine the absorbance of solution

Trial 1 : absorbance = 0.768

concentration of Fe in solution = 1 x 0.768/0.805 = 0.954 mM

mg Fe in vitamin = 0.954 mM x 55.845 g/mol = 53.276 mg

mg of Fe per g vitamin sample = 53.276/1.2502 = 42.61 mg Fe/g vitamin

Trial 2 : absorbance = 1.254

concentration of Fe in solution = 1 x 1.254/0.805 = 1.558 M

Trial 3 : absorbance = 1.263

concentration of Fe in solution = 1 x 1.263/0.805 = 1.569 M

[Correction, the concentration of standard solutions If are in M, the concentration of Fe in unknown becomes very high, so the concentration of Fe in standard solutions are probably in mM]

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