1. Real World: Calcium in Milk
By: Chealsa Mooney and Christina Robinson

2. Purpose
To determine how much calcium was in different types of milk and comparing them to their known values.
Using two different types of indicators and comparing the results they produce.

3. Procedure One Calmagite Indicator
Weighed out EDTA, dissolved in 1000mL. Resulted in M EDTA solution
Created ammonia buffer
In 250mL Erlenmeyer flask put 50mL of milk, 3mL ammonia buffer and small amount of calmagite indicator.
Titrated with EDTA solution.

4. Titration
set up with
Calmagite
Indicator:

5. Procedure Two Patton-Reeder Used same solution of EDTA.
In 250mL Erlenmeyer flask put 10mL of milk, 40mL distilled water, and 4mL of 8M NaOH.
Allowed solution to sit for 5 minutes for precipitate to form.
Added 0.05g of Patton-Reeder indicator when precipitate formed.
Titrated with EDTA solution.

6. Spike Procedure
In 250mL Erlenmeyer flask put 10mL of milk, 3mL ammonia buffer, 1mL spike and small amount of calmagite indicator.
Titrated with EDTA solution.
To test without the spike to see if it produced the same result we put in a 250mL Erlenmeyer flask 10mL of milk, 3mL ammonia buffer and small amount of calmagite indicator.

7. Data Types of milk Percentage of Calcium 1% milk 60% 2% milk 30%
Nonfat skim milk 25%
Lactose milk %
Skim milk %

8. Data Calmagite Indicator Ex: Soy milk Aver: 0.02082g mL of EDTA
Ca2+ conc. (g)
Trial 1
16.8mL g
Trial 2
15.2mL g
Trial 3
13.1mL g

9. Calmagite indicator color change:

10. Data Patton-Reeder Indicator Ex: Soy milk Aver: 0.02267g mL of EDTA
Ca2+ conc. (g)
Trial 1
19.3mL g
Trial 2
13.3mL g
Trial 3
16.5mL g

11. Patton-Reeder indicator color change:

12. Data Spike Ex: Soy milk spike without spike Trial 1 18.4mL 17.3mL

13. Calculations EX: 1% milk Ca2+ concentration in milk
L EDTA x M EDTA x 1mol Ca 2+ x molar mass Ca 2+
1mol EDTA
L x M x 1mol Ca 2+ x g/mol Ca 2+ =
Grams of Calcium per serving
grams Ca 2+ x vol
vol sample serving
g x 240mL = g
50mL serving serving

14. Calculations cont.
Grams of Calcium per serving based on 2,000 calorie diet
mg Ca 2+ (needed daily) x g x %Ca 2+ in milk
1000 mg
11oo mg x g x 60% = 0.66g Ca 2+
1000mg
Percent Difference
Actual - Experimental x 100%
Actual
x 100% = 18.9%
0.66

15. Results: Percent Difference
Types:
Calmagite
Patton Reeder
1% milk
18.6%
26.1%
2% milk
36.9%
12.8%
Nonfat skim milk
102.4%
64.4%
Lactose milk
7.68%
46.2%
Soy milk
79.8%
16.8%

16. Conclusion
- The calmagite indicator took a lot more EDTA to reach the endpoint
-Overall, the Patton-Reeder indicator produced better results although the lowest percent difference came from the Lactose milk using the Calmagite indicator. (7.68% difference)
-Calmagite indicator with the skim milk produced the highest percent difference (102%)
-The spike test produced good results. It took about that same amount of EDTA to titrate samples with and without the CaCO3

17. Sources of error: - misreading the buret - Some trials might
have needed to be
titrated more (blue
endpoint but then
after a minute it
would go back to
purple)
-not letting the milk sit long enough to let the magnesium oxide form. (that's what reacted with the indicator)

18. References
Determination of Calcium Ion Concentration. College of Science. University of Canterbury, n.d. Web. 12 Dec
nts/calcium.pdf
•Harris, Daniel C. Quantitative Chemical Analysis, 8th ed.; W.H. Freeman and Company: New York, 2010, page 240.

19. Questions ?