Spectrophotometric Determination of Iron in Vitamin Tablets Essay

1604 Words Jun 18th, 2012 7 Pages
Lab 2: Spectrophotometric Determination of Iron In Vitamin Tablets

Objectives:
- To determine the amount of iron in a generic vitamin tablet on a per tablet (in grams) basis.
- To prepare standards using a pre-made iron solution to help determine the iron content in our generic vitamin tablets
- Determine absorbances of our vitamin tablets and standards using the spectrophotometer

Method:
1. Mass three vitamin tablets that contain iron
2. Place each vitamin in a 125-mL Erlenmeyer flask with 25 mL of 6M HCl
3. Do the same as above with no vitamin (This will be the reagent blank)
4. In the hood, simmer until the vitamin completely dissolves plus an additional 3 minutes.
5. After vitamin dissolves, allow to cool and then filter
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Looking at my results, for each of the vitamins I found there to be 19.2mg, 7.27mg, and 13.3mg for each of the three vitamins we used. I know when conducting this experiment, we noticed that the final solution for the second tablet (7.27 mg Fe / vitamin), the solution was much lighter than the other two final diluted solutions (with the added phenanthroline, citrate solution and hydroquinone). The color of this solution was not as dark peachy red/orange. This color was a much lighter color not showing so much of a red characteristic and rather a lighter peachy / orange color. Furthermore, I feel that the iron in the third vitamin was not so close to the 18 mg mark because we did stop that one a little bit early. Due to time, the vitamin was not fully dissolved upon taking it off the hot plate, which definitely resulted in a lower amount of iron being found in the solution. Taking the mg of Fe in each vitamin, a ratio was set up with the mass of each tablet to find the amount of iron in one gram of tablet, resulting in 52.5g, 18.9g, and 36.2g for each tablet respectively. In this experiment, I feel that the results I achieved were decent. Like mentioned before, due to stopping short on the third tablet and noticing a different color solution for the second, definitely shows that the results achieved were not to the 18 mg iron par, but were close if it was able to be finished properly. Just by looking at my result for the first tablet, you
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