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Quantitative Analytical Chemistry
Joseph Orlando
Lab #9: Real World Project - Volumetric/Gravimetric Comparative Determination of [Ca^2+] in Teeth
Exposed to Various Beverages.
Purpose:
Determine the Ca2+ deterioration in bovine teeth samples that have been exposed to various
soft drinks and energy drinks. The beverages tested in this experiment were Coca-Cola, Sprite,
Red Bull and H2O. Ca2+ concentration was measured by EDTA titration as well as a gravimetric
method by reaction with ammonium oxalate.
Procedure:
Standardization of EDTA
1. Calibrate pH meter using solutions with known pH.
2. Prepare a 0.01 M EDTA solution
3. Prepare a Ca2CO3 solution by reaction 0.01g of Ca2CO3 with 100mL of 0.1 M HCl. Add 3mL of
this solution, 5mL of ammonia buffer and a few drops of calmagite indicator into a 250mL
Erlenmeyer flask.
4. Titrate the solution with EDTA until a blue endpoint is reached. Repeat titration three times
until three good results are obtained.
Teeth Sample Preparation
1. Teeth were smashed into small enough fragments to place into test tubes containing soda
2.
pH of soda was taken using a calibrated pH meter
3. We allowed teeth to sit in soda samples for one week
4. After one week, teeth were taken out and dried at 120°C for one day
Volumetric Analysis
1.
2.
3.
4.
Three aliquots (3mL) were taken from each soda sample and placed into Erlenmeyer flasks
5mL of ammonia buffer and 3-4 drops calmagite indicator were added to each flask
3mL of Coca-Cola sample was diluted in a 100mL volumetric flask
50mL of this diluted Coke solution was titrated with EDTA
Gravimetric Analysis
1. Remaining portions of solutions were reacted with ammonium oxalate
2. Samples were placed on a hot place with a stir bar
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3.
4.
5.
6.
7.
Data:
After samples began to boil, urea was added
Ammonium oxalate was added
Solutions were heated/stirred for 30 minutes allowing for precipitation
Solutions were vacuum filtrated
Samples were allowed to dry for 24 hours at 120°C
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Equations:
Mass EDTA Needed
0.01 mol EDTA
372.24 g EDTA
× 0.500 L ×
= 0.7306 g EDTA
1L
mol
M EDTA
1 𝑚𝑜𝑙 𝐶𝑎𝐶𝑂3
1
0.003 𝐿
1
×
×
×
100.09 𝑔 𝐶𝑎𝐶𝑂3
0.100 𝐿 𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛
1
. 00955 𝐿 𝐸𝐷𝑇𝐴
= 0.0099 𝑀
0.3161 g CaCO3 ×
Conclusion:
The purpose of this experiment was to determine which beverage causes the most calcium
deterioration in bovine teeth. We initially planned to use human teeth but due to the difficulty
of obtaining human teeth we used bovine. There are studies that prove that the use of bovine
teeth for in vitro experiments is an acceptable replacement for human teeth. The two different
methods that we used produced fairly similar results. The gravimetric method showed that Red
Bull was the worst culprit of calcium deterioration followed by Coke then Sprite, whereas the
volumetric method showed that Sprite was the worst beverage followed by Coke and Red Bull.
The data obtained in this lab clearly proves that regardless of what soda you are drinking, it’s
bad for your teeth. We calculated out that if you were to drink one 12 pack (16oz cans) of soda a
day it would take you about 5.5 years to accumulate this much calcium deterioration. We
propose a need for further research on this topic. If time had permitted we would’ve liked to
have tested the soda samples to determine whether or not the nutritional labels are correct by
saying that they are an insignificant amount of calcium. Also there should be an actual study
done using human teeth and compare those results with the results obtained in this study to
determine whether or not bovine teeth are an acceptable supplement to human teeth in in vitro
dental studies. Finally, we would’ve also liked to have taken samples from the soda samples at
various intervals over the course of a week to see at which point the calcium deterioration
reached its maximum level.